my freind tricked me into playing the star spangled banner for the 3 or 5k run (i forgot) im playing with 1-2 others, so any tips on not screwing up infront of alot of people.

ive sung infront of my highschool before, but singing infront of people i know, and playing something this importaint infront of a ton of people is differnt and i dont want to screw up