create form

Question

hey, i need help with c# i want to create form in c# and i know how to drag button,edit box and etc. (from the toolbox) and automaticly the code is creating - this is simple and i`m understand it.... the problam is : i want to change the code of the form(that create automaticly) and when i add, for example another button, all my changes is disappear how can i avoid ? what should i do? thank you in advance koby