VBGamer

I need help using classes. I have never used them before. I'm making a program with a friend of mine, and we would like to easily send new versions to eachother, without actually sending the whole new source code. So I heard somewhere that using classes allows easier project upgrades. So how would I go about using a class? For example, if I have some mouse_down event code for a picturebox, how would I make that upgradeable via classes? Thx Simon