How to re-associate events functions

Hi, 

How to re-associate events functions like Form1_Load, button1_Click etc?

I created a simple win-form Form1, add label, text, and button button1. Then I copied Form1_Load, button1_Click from somewhere else into my code behind, but those functions are not associate with the windows events that it supposed to be?

How can I establish the association between my copied code and its corresponding windows events?

Thanks