c#: search in string array and get specific string value

I want to search through an element value in xml file and get the specific string out of it. For instance, I have the following element value in my xml file:

<Content>Shape="Rectangle" Tooltip="data" StrokeThickness="2" Tag="default" </Content>

Now I want to read this Content and get Tooltip value as my resulted string, that should give me "data". I want something like:

string restuledString = Tooltip.value

How to do it?