How I Have To Separate Integer With Commas Like (1234,212,123)

You need to tell ToString two things: 1) what culture should be used to produce certain type of separator, 2) indicate what to use for the separator; it could be the default for the specific culture.

Please see:
http://msdn.microsoft.com/en-us/library/system.globalization.numberformatinfo%28v=vs.110%29.aspx[^],
http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo.numberformat%28v=vs.110%29.aspx[^],
http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo%28v=vs.110%29.aspx[^].

You can also define the culture to use for the current thread:
http://msdn.microsoft.com/en-us/library/system.threading.thread.currentculture.aspx[^],
http://msdn.microsoft.com/en-us/library/system.threading.thread.currentuiculture.aspx[^].

The most customized way of having any separators with any number of digits is shown in this article: http://social.msdn.microsoft.com/Forums/vstudio/en-US/8e1b235f-c10e-49f9-8c4f-13af717944fe/number-format-string-thousands-separator-with-any-number-of-decimal-places?forum=csharpgeneral[^].

Please see:
http://msdn.microsoft.com/en-us/library/dwhawy9k(v=vs.110).aspx[^],
http://msdn.microsoft.com/en-us/library/0c899ak8(v=vs.110).aspx[^].

—SA