Workouts are held:
Summer workouts return every June, consisting of the addition of morning workouts
Workouts usually mainly consist of a warm-up set, followed by a main set, a kick set, a pull set, and ending with a cool-down set. Kickboards are provided but pull buoys and hand paddles are not. Typically the slower swimmers swim in the lanes at the east end of the pool and faster swimmers take the far west lanes; workout sets are modified by lane for swimmer ability.
In general the swim club is for people who already know how to swim freestyle/crawl and at least one other stroke. Knowing how to swim means that you feel comfortable swimming back and forth across the pool repeatedly. The speed at which you go is not all that important. The coaches are great at teaching better stroke techniques and things like flip turns. If you want to learn more just ask one of the coaches. If you don't know how to swim it would be better for you to take a class that teaches people how to swim. All members of the Caltech community can take such classes through the physical education department.