In order to work with Windows controls and to be displayed, your class must be a Control itself - i.e. it must derive from Control in order to get a windows and a message loop. The usual way this is done is to create a UserControl class, and drop your form controls onto that. UserControl Class (System.Windows.Forms)
If you are not trying to create a control that can be displayed, then you would treat it as a normal class: you get and set data via properties, and cause it to do things via methods. We can;t explain all that to you - if you have been a developer for 7 years and you don't understand such very, very basic things then you really need to get a book and read it from cover to cover, because it's clear you have missed out far, far too much stuff somewhere...