Don't be so fecking immature.
Either he was to forceful entering you or there was not enuff lube. When participating in anal s
ex, it is important to be very relaxed, use lots of lube and take your time when teh other person enters.
It is also very important to remember there is only one layer of skin in the anus, it can be ripped very easily, causing septic poisining for teh receiver.
So just remember, next time use alot of lube and don't rush into it, it takes time, and if you bleed again then I'd be going to see a doctor.