So do you stick your entire finger in there? Is it similar to fingering a woman?
Stick as much of your finger in as feels comfortable to him. Ask him to communicate what feels good to him, and what does not. If he enjoys the sensation, you can then move on to more fingers, and possibly toys.
It can be similar to fingering a girl, but then again that depends on the technique used when fingering a girl. There is variety to both.
jaquen: What was your first time like? Was it strange at all?
First time with myself, or with a woman?
With myself, yes, it was definitely strange, both mentally and physically. I was a teenager, and curious about the sensation. I had a lot of insecurity about even trying it on my own, bullcrap homo fears and all. Initially I didn't feel anything but discomfort. But I was really into learning my body back then, and so I persisted. When I finally hit that "sweet spot" moment, it was like a lightbulb going off. It is a very intense kind of pleasure. Eventually I ended up sticking all kinds of strange stuff up my ass!
The first time I had any anal play with a woman was two years ago when my wife just decided, on her own, with no prompting or asking from me, to throw back my my legs and just lick my anus. It was...incredible
Also keep in mind that you do NOT need to insert anything in his rectum in order to pleasure his prostate. Pressing down on the perineum, the space between his scrotum and anus, while he's aroused can produce similar results without needing to penetrate him.