Gala Event

I have to design a data base for a Gala Event.

I need tables for:

Entrants
Judges
Sponsors
Categories
Results/Event

I take it the above will be my five tables. Can someone identify the
primary keys here for me and the relationships between the five
tables? I have tried but always end up with one relation being
indeterminate.........!

It is getting very frustrating now

Brenda