C#, form showing & closing

I have some forms, 1 login form (let's call it A), 1 menu/selection form (let's call it B), and 2 or 3 data forms (C,D,E). A will call B, B will call C or D or E C and D and E will have buttons to log out (back to A), go back to B (main menu), and Exit (close application). I need a sample project to do all above properly.