That'll happen in time. You have to figure out what works with the person you're with. All names have been changed to protect the no-longer innocent. L. Chad encourages all readers to be sure you're ready before you do it. However, if you are a guy, then most likely, you aren't as small as you think you are.
MANY guys are uncomfortable with their size and it's usually for no reason.
Usually most if not all of penises guys see is from porno movies and those guys are huge, yes, but they are also rare, never compare yourself to them as a standard because you will most likely be coming up short. But girls also dont usually care that much about size. Almost none of them would ever say that to you anyway. Find the right girl to have sex with and it wont matter. Be comfortable with them first, once you feel comfortable to be naked in front of them.