How to call Server Side function from Client Side Code using MASTERPAGES!!

I have see this 3 topics:
http://www.dotnetcurry.com/ShowArticle.aspx?ID=109

http://decoding.wordpress.com/2008/11/14/aspnet-how-to-call-a-server-side-method-from-client-side-javascript/

http://weblogs.asp.net/muhanadyounis/archive/2008/12/30/scriptmanager-and-masterpage-pagemethods.aspx



And just the 3 use MasterPages, I can´t find any article that explain to me an interaction betweeen client side, and server side using MASTERPAGES.
My all web site use master page, and i really need to acess from client side using javascript to some functions in server side, the big problem is.. i use MASTERPAGES  i read the 3 article ...