Blu is right, the first step is to take a home pregnancy test. The second is to make an appointment with an ob/gyn regardless of the result. If it's positive, you'll need to start deciding about keeping it, giving it up for adoption, or getting an abortion. If it's negative (and the ob/gyn confirms it), then you need to have a talk with them about your birth control options.
Condoms are ALWAYS a good idea, especially if you're not in a committed relationship. There's nothing inherently wrong with sleeping with your guy friend casually, but you need to be responsible about it. Condoms protect you from getting pregnant, and they protect both of you from disease (since it's possible to have something and not know it yet). You should also think about getting hormonal birth control or a copper IUD as backups that you have control over. There's the pill, the patch, the NuvaRing, the Mirena IUD, the copper IUD, depo provera, and the implant to name the main ones. Your gyn can talk to you about the benefits and drawbacks of each. I stay on the pill regardless of my sexual activity, because it keeps me from PMSing, greatly reduces my cramps, and lightens my period. And I can skip my period if I want.
You're currently listed as male, by the way. It seems to happen a lot, just go edit your profile to fix it.
Alright, let's be rational about this. Facts are that you had unprotected sex, no condom, no birthcontrol. This causes the possiblity of pregnancy. Therefore, your next step should be to test yourself at home, and if yes, have yourself re-tested just to be sure. If no, then if it were me, l would think about being more careful next time. God Bless - Blu