Explain some image with a nice manual

I have an Application but I need to make a manual, is a small application just 5 screens, but I need to make a very visual manual, something nice and easy to understand, the application is pretty simple, but I will use this manual on my web page for selling proposes I need Explain the functionality of each screen in few words and in a nice and graphic way and explain the measured os each item in the screen(because each user can change the size of the buttons and menus, something like [login to view URL] ) That is all