too tight to ride .. or sex period :/

so the other night me and a new fling tried having sex. he wanted me to “sit on it” but i’ve nvr done that so i was nervous. we were in the car so space was limited and it was dark out so i couldn’t see. i tried putting it in but it wouldn’t go. once i finally got it in, the pain for me was kinda harsh. i just felt like i was tearing and losing my virginity all over. it’s been ab 5-6 months since i last had sex so idk if i closed up or something. we didn’t try missionary bc he can’t get hard enough for that position. we didn’t try any others either bc we were in the car.

i’ve heard great things about riding and i want to try so bad. are there any tips for me to try to get it in and enjoy ?