The event registration is covered in the database starter kit tutorial starting on slide 29. In here is a good description of the tables and what they are used for. I did not see any info for the types table, it seems to be just a generic table for types not relating to the others. The tracks table is covered in this as well.
This is the only info that we have for these tables, if you have any other questions about them taking a look at the structure with your GUI tool may give you a better understanding of how it all works.