Mildly freaking out first time coach

Hey y’all just need to vent somewhere! I am a first time coach and have 10u girls. My son is playing 10u as well. Today is our first game and I’m freaking out. I don’t feel like I have a clue what I’m doing and not even sure I will have enough players! We have only had 3-5 show at every practice. I have 7 out of 10 say they coming to the game but several have said before they coming to practice and not show. I don’t know all the details on when to do what and the girls barely know positions. It’s hard to show them positions when there isn’t enough at practice. I don’t want to fail the girls but feel like I am!