I'll have a go -
1. Boats on the Port tack must keep clear of boats on Starboard tack. (Additionally, if a port tack boat is keeping clear, a starboard tack boat can't change course in such a way as to cause the port-tacker to act again to continue keeping clear - no hunting.)
2. On the same tack - Clear astern keeps clear of Clear ahead.
3. Boats on the same tack AND overlapped : the boat to windward of the other must keep clear. (Additionally - if you gain an overlap TO LEEWARD of another boat from clear astern, you aren't allowed to sail higher than your proper course - i.e. the best possible course toward the next mark.)
4. While tacking, you must stay clear of other boats until you are on your new close-hauled course. (If your new course is close-hauled on port tack, look out for starboard tack boats...)
5. Mark roundings : this is where things get a little complicated...
The rules define a 3 boat-length ZONE around marks.
If boats are overlapped when the first of them enters the zone, the inside boat is entitled to room to round the mark and the outside boat must stay clear (no matter what tack either boat may be on.)
If no overlap exists, the boat clear astern must stay clear and is NOT entitled to try to round inside at the mark.
EXCEPTION : The above mark rounding rules do NOT apply at a windward mark between boats on opposite tacks beating to windward or if the proper course for one of them is to tack. Example : Two boats are approaching the windward mark - one on port the other on starboard, and they will be passing the mark, leaving it on their left side (therefore the boat approaching on port will have to tack to round the mark.) The port tack boat is not entitled to room. She must stay clear of the starboard tack boat both before and while tacking, and she must not force the starboard tacker to sail above close-hauled while the mark is being passed.
6. Penalties : the penalty for breaking a rule is a 360 degree turn - i.e. one tack + one jibe.
That's pretty much the basics - some of the terms might be foreign to you. Feel free to ask.
Hope this is helpful -