Basics: After every round of golf, whether 9 holes or 18 holes, enter your score into the GHIN system. Most of us use the GHIN app on our phones to do this. GHIN will compute your Handicap Index on a daily basis. Your Handicap Index (H.I.) is a number used to represent your potential scoring ability, which is always expressed as a number taken to one decimal place (e.g. 10.4).
Your Course Handicap is computed from your Handicap Index and is a function of the difficulty of the course and set of tees that you are playing. This number is used to calculate how many strokes you would potentially need in order to adjust your score back to par. The course handicap allows golfers of all skill levels to compete on an even playing field. It is easiest to use the GHIN app on your smart phone to determine your course handicap before you play a round (your H.I. is updated the day after every round that you play, so your course handicap may change frequently).
Your course handicap varies from course to course and from one set of tees to another. For example, if you have a 19.8 Handicap Index, then your course handicap at Audubon would be a 19 from the White tees, 16 from the combo tees, and 14 from the Gold tees.
When playing in a competition, whether an Audubon Club event or just a casual Sunday round with buddies for a pop, the course handicap levels the playing field between players, regardless of which tees each of you are playing from. Note that in such a competition, if there are players with handicaps of, say, 8, 10, 11, and 17, then everyone "plays off the lowest handicap," which means those players get 0, 2, 3, and 9 strokes, respectively. So, if you look at the scorecard, the player getting 9 strokes, will get 1 stroke on the hardest 9 holes, which are listed on the scorecard as holes ranked 1 thru 9.
In terms of entering a score into the GHIN system, it is best/easiest to enter your full score hole-by-hole. That is, if you took 13 strokes on a hole, enter the 13 - the GHIN system will reduce that to the correct value for purposes of correctly computing your Handicap Index. This avoids most common errors.
If you do decide to enter a single score into the GHIN system, then please note that the most strokes you can count for a hole towards your Adjusted Gross Score is "net double bogey." Net Double Bogey for a hole is par for that hole + 2 strokes for double bogey + the strokes that you get for a handicap on that hole. That is, if you get 0 strokes on a par 3, the most you can enter on GHIN towards your Adjusted Gross Score is 5. If you get 2 strokes on a par 5, the most you can enter on GHIN towards your Adjusted Gross Score is a 9.
It is important to count and record all strokes when playing in a club competition, including all weekly events. So, if you made a 17 on a par 3, then all 17 strokes count in your score that is reported for the club competition. This is different from what you would enter into the GHIN system for handicap purposes - again, entering the 17 for that hole into GHIN is safest as GHIN will determine that net double bogey is for you.
Finally, the USGA requires that if you play at least 7 holes, but less than 14 holes, then you must post a 9-hole score, using par plus your handicap for any of the 9 holes that you did not play. If you play at least 14 holes, you must post an 18-hole score, again, using par plus your handicap for those holes you did not play.