how to set the initial selected fragment?

I have created a fragment that contain 5 more fragments by using images.

However when I enter the default fragment, it did not select any initial fragment.

fragment_main.xml

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://ift.tt/nIICcg"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1" >


        <fragment
            android:name="gymbuddyV3.gymbuddyv3.FragmentSearch"
            android:id="@+id/fragment_place"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:background="#000000" >

        <ImageButton
            android:id="@+id/btnSearch"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="14dp"
            android:background="@android:color/transparent"
            android:onClick="selectFrag"
            android:src="@drawable/searchfill" />

        <ImageButton
            android:id="@+id/btnBrowse"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="14dp"
            android:background="@android:color/transparent"
            android:onClick="selectFrag"
            android:src="@drawable/browse" />

        <ImageButton
            android:id="@+id/btnCheckin"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="14dp"
            android:background="@android:color/transparent"
            android:onClick="selectFrag"
            android:src="@drawable/checkin" />

        <ImageButton
            android:id="@+id/btnProfile"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="14dp"
            android:background="@android:color/transparent"
            android:onClick="selectFrag"
            android:src="@drawable/selfs" />

        <ImageButton
            android:id="@+id/btnBuddy"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="14dp"
            android:background="@android:color/transparent"
            android:onClick="selectFrag"
            android:src="@drawable/friends" />
    </LinearLayout>

</LinearLayout>

MainActivity.java

     public class MainActivity extends Activity {
        public static final String PREFS_NAME = "LoginPrefs";
        ImageButton btnSearch, btnCheckin, btnProfile, btnBuddy, btnBrowse;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_main);

        btnBrowse = (ImageButton) findViewById(R.id.btnBrowse);
        btnSearch = (ImageButton) findViewById(R.id.btnSearch);
        btnProfile = (ImageButton) findViewById(R.id.btnProfile);
        btnCheckin = (ImageButton) findViewById(R.id.btnCheckin);
        btnBuddy = (ImageButton) findViewById(R.id.btnBuddy);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == R.id.itemLogout) {
            SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
            SharedPreferences.Editor editor = settings.edit();
            // editor.remove("logged");
            editor.clear();
            editor.commit();
            Intent i = new Intent(getApplicationContext(), LoginActivity.class);
            startActivity(i);
            finish();
        } else if (item.getItemId() == R.id.itemLeaderboard) {

        } else if (item.getItemId() == R.id.itemSettings) {

        }
        return super.onOptionsItemSelected(item);
    }

    public void selectFrag(View view) {
        Fragment fr;
        if (view == findViewById(R.id.btnBuddy)) {
            fr = new FragmentBuddies();
            btnSearch.setImageResource(R.drawable.search);
            btnBrowse.setImageResource(R.drawable.browse);
            btnCheckin.setImageResource(R.drawable.checkin);
            btnProfile.setImageResource(R.drawable.selfs);
            btnBuddy.setImageResource(R.drawable.friendsfill);

        } else if (view == findViewById(R.id.btnProfile)) {
            fr = new FragmentProfile();
            btnSearch.setImageResource(R.drawable.search);
            btnBrowse.setImageResource(R.drawable.browse);
            btnCheckin.setImageResource(R.drawable.checkin);
            btnProfile.setImageResource(R.drawable.selfsfill);
            btnBuddy.setImageResource(R.drawable.friends);


        } else if (view == findViewById(R.id.btnCheckin)) {
            fr = new FragmentCheckin();
            btnSearch.setImageResource(R.drawable.search);
            btnBrowse.setImageResource(R.drawable.browse);
            btnCheckin.setImageResource(R.drawable.checkinfill);
            btnProfile.setImageResource(R.drawable.selfs);
            btnBuddy.setImageResource(R.drawable.friends);

        } else if (view == findViewById(R.id.btnBrowse)) {
            fr = new FragmentBrowse();
            btnSearch.setImageResource(R.drawable.search);
            btnBrowse.setImageResource(R.drawable.browsefill);
            btnCheckin.setImageResource(R.drawable.checkin);
            btnProfile.setImageResource(R.drawable.selfs);
            btnBuddy.setImageResource(R.drawable.friends);
        } else {
            fr = new FragmentSearch();
            btnSearch.setImageResource(R.drawable.searchfill);
            btnBrowse.setImageResource(R.drawable.browse);
            btnCheckin.setImageResource(R.drawable.checkin);
            btnProfile.setImageResource(R.drawable.selfs);
            btnBuddy.setImageResource(R.drawable.friends);

        }

        FragmentManager fm = getFragmentManager();
        getFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
        FragmentTransaction fragmentTransaction = fm.beginTransaction();
        fragmentTransaction.replace(R.id.fragment_place, fr, "selectedfragment").addToBackStack(null).commit();


    }
}

One of the fragment.java class

    public class FragmentSearch extends Fragment {
        Spinner spnLocation, spnDate;
        Button btnFind;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_search, container, false);
        spnLocation = (Spinner)view.findViewById(R.id.spinnerLocation);
        spnDate = (Spinner) view.findViewById(R.id.spinnerDate);
        btnFind = (Button) view.findViewById(R.id.btnFind);
        // Inflate the layout for this fragment
        return view;
    }
}