yea, correct me if i'm wrong, the masterpage is the "DEFAULT" page and then i create other pages that "inherits" (i know is not inheritance, but just an example in order to explain what i know) from the masterpage. For example if i have a masterpage with header and footer as master.master with a contentplaceholder in the body. Then i create a login.aspx with master.master as the masterpage and include my independent code inside of the container of login.aspx. When i run the webpage, the masterpage creates the proper HTML. I realised about the forms, when you create a new .aspx file, with the default code. It shows something like this:
// Here I should add all the ContentPlaceHolder's right?
And manage all the events from each page without needing a lot of forms. Thanks again :D Marian.