Paul,

The blue screen is how your database would look in Q&A for DOS. You are in runtime. You make changes to your database in Designer. There is a button on the Application Menu near the bottom that says Redesign Current Application. This will make a design copy of your app and open it in Designer where you can make changes. When you are done making changes, you can reconcile them back to the working copy of your app.

The Quick-Start Tutorials will give you a general look at Designer and how it works. As to generally using Designer, chapter 3 in the User Guide may be of use to you. Combo boxes are on page 85.

In general, you may find some of our One Sheet references useful.
http://www.lantica.com/Support/sesame_library.html

If you are interested in really hitting the ground running, I have some beginner level training classes for Designer, Reports and Programming that have been very well received. If you are interested, they might be of help to you to get you started.