The Personal tab is all about you. You can set where and when you've seen a movie, set your own rating, add some comments, etc.
If you have a movie on your computer, you can add the movie file to the database. Choose File ▶ Choose File, or just drag the movie file to the location field. If you have a movie on disc, you can select a format: DVD, Blu-ray, etc.
There are also four custom fields that you can use for any purpose you like. For example, you could store who you saw a movie with, whether you had popcorn or candy, or anything else you can think up. You can edit the field labels by clicking on them. Each of these fields remembers recent values, and will automatically complete your typing.