preparing for anal

Raquel
Okay so my boyfriend has been wanting to have anal sex and I'm into the idea.  We've tried it before but it really hurt so we didnt do it very long.  I'd like to try it again but I want it to be as enjoyable as possible.  He also has a large penis (thick 8/9 inches)
How should we go about it?  
Should do an enema? How do I do it myself?
What else would make it more enjoyable for me?