The racing rules of sailing are written to be unambiguous, concise and complete. This lawerly language is sometimes a bit hard to understand, so here are the basics:

• Be safe and responsible.
  
• When boats approach each other the right-of-way rules says who must yield.
• Port tack must yield to starboard
• If overlapped the windward boat yields to leeward
• Clear astern must yield to the leading boat
• A tacking boat must yield to all others
  
• At the marks, except the start, the outside boat must leave room for the inside boat if they were overlapped when they crossed within two boat lengths of the mark.
• If you start early, hit a mark or foul another boat you have to do penalty turns
• Back across the starting line for an early start
• One complete circle for hitting a mark
• Two turns for fouling a boat

That's it in a nutshell.

A couple of other thoughts about the rules:

• Yelling at other boats to remind them of the rules is always a good idea.
• If you aren't sure some one else is bound to know, they might even be right.
• The rules contain stuff about flags that seems quaint, but is actually used.
• There might be boats in the same water with you that aren't in the race.
• Really big boats always have the right-of-way, even when they don't.