Calling a method in FORM class from another class

Question

hey anyone tell me how to call a method in FORM class from another class but both under same namespace.i have some text information which is to be displayed in the textbox through from class by calling a method in form class.i'm ew C# can anyone help me out. i tried in all d ways i could...but no use...its screwing my mind...please someone help me out...
thanks in advance........