That's something your instructor should teach, as they are basic moves. Here's a few tips in the meantime:
1) Don't panic!!! He wants you to waste energy trying to escape. Take your time, but don't get lazy. You should be controlling the pace not the other person, as always.
2) When making space, but one forearm on the hip and the other on either the closest neck or armpit. Then push with your elbows not your hands. This (1) gives you more power (2) safer from armbars/keylocks/kimuras.
3) Bridge to make more space, but not too much. Gotta be quick so a pocket forms.
4) Shrimp away to get even more space and to get a knee in. You can shrimp back while keeping your knee in and get half-guard. Then do one of the million half-guard escapes.
5) If he puts his knee on your belly, DO NOT try to push it off with your hand. That is an error; although, I forgot the reason (sets up an arm bar or cheese gratter I think).
I'm not anything but an average white belt, so perhaps someone more experienced can confirm these tips or offter better ones. Good luck!