Hi Hissa, if you're a little uneasy about your first canter, it may help heaps to have someone hold your horse on a lunge line so you don't have to worry about steering your horse. That way you can focus on keeping your balance, and as Lian already mentioned, to keep breathing 😊 a lot of riders try to hold their balance on the reins, you can put a martingale or stirrup leather around your horses' neck to hold on to instead of your reins. Also remember to enjoy, and be proud of how far you've come up to your first canter! Good luck!
I would stay relaxed as the more tense you are the more likely to have a bad experience make sure to breathe as I see a lot of beginners that I help do not breathe. Keep your heels down and if you don’t feel secure keep your inside hand (hand closest to middle of arena) on the saddle and hold on and use your outside hand (closest to the wall) to steer
Hope this helps