I'm A 24 Year Old Virgin Male. Had Two Recent

I'm a 24 year old virgin male. had two recent sexual experiences. First time I thought I had too much to drink and that was why I didn't get an erection. Few days later we started to have sex but I still couldn't get quite hard enough, although it was better than before. As an admission, I have in the past used prone masturbation techniques and ever since these sexual experiences I've realized it is harmful. What can I do to ensure i can perform?