you can get nervous if you want to ahah but just know this: once you get into the arena all of it will go away and the only thing you will think of is what youre supposed to do. good luck
If you feel stressed try yoga or any other relaxation method. Don't worry about your result and do it for fun. Feel confident. :)
It's your first show, just absorb how it works and enjoy it
What I do is I pretend I'm just hacking my horse and relax as much as possible, I trust my horse and act like we're just hacking and working on things.
When I did my first show I tended to look at other people but I learned it was better to pay attention to me and my horse so stay focused and don't rush into things take your time
Pretend like it's just you and your horse...and maybe your trainer.
Keep clam, have fun and just enjoy it. Don't worry about not placing or anything like that just go out and have fun. Maybe see if any of your friends are going to the same show and if so maybe warm up with them or have a chat before you compete or ask if they can watch you. Sometimes have a supporting cheer squad can make you feel 100% better even when things go wrong
When I went into my first show I was immediately calmed knowing I had my partner with me, my horse. Before any show, I like to check up on my horse and stay with them as much as possible so to keep me calm. They just have their own way of keeping me sane