First of all, you basically don't need anything, because the wetsuit and equipment is provided by us. If you want to take a shower, we have changing rooms with showers, you will only need to bring your personal stuff.
Secondly, the classes are of 2 hours and the group will be of 3-4 people maximum, if you come alone we will join you to groups that we have already made or that we are forming. The classes will be held every day if the weather permits. The general class start times are 12:00, 15:00 and 17:00h, so you should arrive 15 minutes in advance.
And thirdly, we depend on the weather, so there may be last minute changes and cancellations, if for safety (or lack of wind) so we estimate. It is advisable to bring flip-flops to move around the Marina. The classes will be held on the Las Arenas beach or in the inner Darsena of the Marina of Valencia, as we deem best.