I took my sailing lessons at OCSC in Berkely, and on day one they were teaching us to reef sails, (make the mains'l smaller). It's a standard part of sailing there, and is key to managing stronger winds. Summer on the Bay are windy! (That's part of why it's such a great windsurfing destination.)
Tons of ways to learn how to reef-it's in all the sailing books, you can do an internet search, etc. (The boat has to be set up for it with reef points in the main, reef lines
, etc, and all of this will be in the books/web sites as well.)
And since it is seldom windy on the Bay in the summer until the afternoon, you'll be able to get out and practice reefing in the light morning winds until you get comfortable, and then get out in the higher winds.
Another key point-if you're leaving your slip and it's already windy, reef before putting out. It's always easier to "shake out"/un-reef the main as the wind dies, than to reef it when it's windy.
Another key point-if reefing crosses your mind because the wind's building, do it then-don't wait.
"Heaving to" is a another skill that goes hand in hand with reefing-you can heave to and calm the boat down while you reef.