The best place to start will be in the Thursday evening races inside the Turning Basin. Jib and Main only. I think they still have a cruising class which will be the most low key.
Looks like you'd be in Div 5 -
Did your buddy who sold you your boat race ? If yes, then have him drive.
If not, you will want to first have some one drive who is an experienced racer.
1) do not buy anything for your S30 until you have raced the beercans for at least 12 months
2) do not race drive yourself until you have participated in, say, 10 races.
3) do not have expectations that you will finish anywhere but D F L for a long time
4) enjoy enjoy enjoy
5) have fun
6) keep it light hearted