When you first launch RiddleMeThis you should see a window with four large buttons.
New Form. This button creates a brand new questionnaire. Simple.
Edit Form. This button allows you to open an existing questionnaire and change it.
If you make cosmetic changes to a questionnaire (e.g. modify the wording or rearrange the questions) data already gathered with that questionnaire will be unaffected. You can even add or remove questions, or replace a question with a new question (with the same column id) and then continue to gather data that can be tabulated with pre-existing data. (Of course, you may not want to do this -- but you can!)
Run Form. This button allows you to run a Questionnaire. You can also create "standalone" questionnaires that run automatically without having to go through this.
View Data. This button allows you to look at the data gathered by a questionnaire. It lists every session completed and allows you to view each session, or export a single file with all the sessions tabulated.