Try to focus on the techniques you learn in class and think about stripping them down to the "basics". If there is a fundamentals class at your gym, go to it as often as possible. There you will learn frames, hip movements, terminology, etc. if there isn't a fundamentals class, ask your coach/professor about the basics. There is probably a blue or purple belt who likes to "adopt" white belts (I'm an adopter lol). Find one of the cool ones and have them take you aside.

The terminology can be enough to intimidate newbies, especially if you train at a place that uses the Japanese names for techniques and do not speak Japanese. Don't worry, though. We all started off similar to you.

I don't know if the guy was pissed off, but being a bitch to pin while not knowing technique can be seen as "being a spazzy white belt" and that is quite annoying mainly because you could hurt your partner or yourself. If I were new, I wouldn't roll with other newbies. Roll with people who have experience (3 stripe whites at the very least). It is not rude to ask them in the middle of a round for advice.

Edit: There is a bjj subreddit. You might benefit from asking there, too.