Condom

I tried to have sex with my new bf and there was an air bubble in the end of the condom and it would no go in me. he also did not stay hard. he stayed hard for like a minute than just dropped it

what am i doing wrong?

Read the instructions on the condom packet.
Squeeze the tip of the condom so there's no air in it before placing it on the tip of the penis and rolling it down.

Penises aren't always rock hard 100% of the time. Erections come and go.
The penis usually needs continuous physical contact or stimulation to stay hard. So if it goes soft, just give it some attention to make it hard again.