Start from "Working with Base Types" (http://msdn2.microsoft.com/en-
us/library/7wchwf6k.aspx):
- "Formatting Types" (converting to language specific formats)
- "Parsing Strings" (converting from language specific formats)

Here are some parsing example:
http://msdn2.microsoft.com/en-us/library/xbtzcc4w.aspx
  using System.Globalization;

  string MyString = "123,456";
  int MyInt = int.Parse(MyString);

And some formatting example:
http://msdn2.microsoft.com/en-us/library/dwhawy9k.aspx
  using System.Globalization;

  int    integralVal = -12345;
  double floatingVal = -1234.567d;

  string msgFloatingVal = floatingVal.ToString("F")); // see also E,F,G,N,P
  string msgIntegralVal = integralVal.ToString("D", ci)); // see also X

This should get you started :-)
Mihai