You need to make your textboxes public, or add some properties or delegate events that allow the transfer of data between the two classes. In the second message you are trying to call a non-static method of the class without an object reference. This is basic C# object handling which you really need to understand before you go much further in this development project. Take a look at these samples[^] for further details.
One of these days I'm going to think of a really clever signature.
