i'd be wary of trying to have sex if something is still makeing your feel afraid.
sex is something you need to be 110% sure about before undertaking it. it's not just wham, bam, thank you ma'am, it involves a lot of responsibility (health issues for you and your partner, feeling and emotions, and a whole lot of planning should anything go not-according to plans)
check out these articles, and take their words seriously.
http://www.scarleteen.com/sexuality/firsttime.html http://www.scarleteen.com/sexuality/safer.html http://www.scarleteen.com/sexuality/readiness.html
you don't have to be with the love of oyur life. If it's a one-night stand, it's a one-snight stand. But can you handle obtaining condoms and lube without embarrassment or fear of punishment? Can you go to your doctor and ask for a full STD screen every 6 months? Can you safely ask your partner all the important questions (have you been tested recently? do you have any infections? are you of legal age for consent? etc.). Does discussing sex, especially safer sex, with your partner make oyu uncomfortable? if she for any reason *does* get pregnant, do you have the $$$ and resouces to support a child, or pay for an abortion? If you for any reason get an infection like HIV, can you pay for treatment?
These are all important things to think about. Sex is a heavy task and shouldn't be taken lightly. After all, it's not just *your* body, but it's also someone else's body, too.
So chew on that for a while. Decide if this is absolutely what you want to do, and if it's the right thing for oyu to do. Otherwise, explore your own sexuality via other means, masturbation and the like.
"Things are only fragile till they break."