Don't worry! Bleeding a little and having mild stomach pain is normal after having sex for the first time.
The bleeding you're experiencing is probably your hymen, which is a membrane that partially covers the vagina. It can be broken during sex, which I guess why people call losing your virginity 'popping your cherry', but the hymen can be lacerated through doing exercise or even inserting a tampon, so it's not a sure-fire way to show whether someone's a virgin or not.
What can you do for the bleeding and pain?
The best thing to do is probably take some pain killers, like paracetamol or ibuprofen, until the pain goes away, and wear a pad. The stomach pain should stop soon, don't worry!
What if it doesn't go away?
If you keep bleeding a little and having stomach pain it might be worth going to see your doctor. It is common for ladies to contract UTIs (urinary tract infections) after sex, and this could be a cause of you prolonged pain. But it's more than likely that once your body has got used to the fact that you've lost your virginity, the pain and bleeding will stop.
Hopefully you use contraception during your first time, but if you didn't, they could be early signs of an STI. I'd get yourself checked out if you're unsure.
You might find some of the answers on this question useful: http://relationships.blurtit.com/1062704/how-long-do-you-bleed-when-you-get-your-cherry-popped
This might be helpful to you as well: