When your number one supporter (boyfriend, dad, or husband) decides to come watch you at their first event, there's a protocol you'll want to ensure you follow if you want them to ever come again.
First off, they are going to want to know what they're watching, but they don't want to know the intricate details of a half halt. I have found the best way to explain dressage is compulsory ice skating where everyone does the same routine and the judges use their discretion to judge each movement on a 0-10 scale. Have them watch your ride only, as dressage can be like watching paint dry if you're not a horse person. After your ride, point them towards the nearest brewery/BBQ joint/golf course.
For cross country, tell them to think of it as motorcross on steroids. Encourage them to watch the highest level at the venue, if that's not the level you are competing in already. They may actually enjoy this part, especially if you have them watch near the water jump. They will most likely see what they call "thrills and spills." Bear in mind that they may not be so supportive of your cross country endeavors depending on what they see. After an adrenaline-filled day, again, point them to the nearest brewery/BBQ joint/golf course.
For the final phase, explain to them that showjumping is all about leaving the sticks up and not having any refusals. The round doesn't have to be pretty, but it sure makes everyone feel better when it is. When showjumping is over, point them to the venue's trade fair to purchase a souvenir hat (if you did well, of course).
Another rule of thumb is don't ask them to help you with anything horse-related (except for putting in studs- they're really good at that!). This will surely save you from an impending argument.
At the end of each day, even though you will be exhausted, wining and dining is a must. I promise it will make the weekend go smoother, even if you do lose an hour of sleep.
Most importantly, at the end of each day, make sure to thank them for coming. They probably have a million things they would rather be doing but ultimately they want to be there with you.