As you'll recall from the tutorial, initial creation of a match is done with a wizard procedure.

If you need to change things later, click the Match Setup button or hold Alt and press F8.

 

 

If you have a tall enough computer screen, you may want to stretch this window to see more matches.

Highlight the match you want to modify, and click Change A Match or hit Enter.

B in the column to the right of the maximum strings per stage column indicates that the match has BUG stages (or BUG renamed as a side match.)

The Misc column shows which matches are hidden, which use the Event module, which are Classifiers that have been committed.

If you have more than one match on a single date, the second match's web and PDF files will have the letter 'A' added to distinguish them from the first match's results. That's shown in the column to the right of Misc.