Take N-IV highway to San Fernando. Whether heading north or south, look for the rotary with a big, boxy, metal sculpture of the world. Take the southern exit off the rotary. Follow this road to the beach (the bike path will tell you you're on the right road). There are a couple of parking lots, take your pick depending on which sand bar is breaking.
If you know a little spanish and the rules of surfing, you shouldn't have any problems. A few dix in the water but most are cool. No surf during the summer but lots 'o' boobies!