How to format XML using WriteStartDocument WriteStartElement WriteAttributeString in C#?

I want the XML in format like:

<?xml version="1.0" encoding="UTF-8"?>
<ftc:A xmlns="urn:oecd:ties:stfatypes:v1" xmlns:ftc="urn:oecd:ties:a:v1" xmlns:xsi="http://ift.tt/1wOXoHY" version="1.1" xsi:schemaLocation="urn:oecd:ties:a:v1 aXML_v1.1.xsd">
    <ftc:b>
        <z>1</z>
        <x>CO</x>
    </ftc:b>
</ftc:A>

I've had trouble writing the attributes whit the methods:

writer.WriteStartDocument ();
writer.WriteStartElement ();
writer.WriteAttributeString ();
writer.WriteElementString ();

I just need the example in C# please :)