Hi Merryn,
This place is a pretty good one for insight and information. I'm not all that active on here but everyone has been very warm and welcoming. My wife is a member here (though I don't think she's posted yet.)
From his perspective, it sometimes can be difficult to answer the questions. I know sometimes it is for me. My wife has asked me a LOT of questions over the last 2 years or so that she has known - and at times it was difficult to answer. He may still be coming to grips with it himself. I know for me, it's just something I've always done in secret for almost as long as I can remember. Since it was just me, and it was secret, I never really had to answer questions about it - I just did it because it felt good. *shrug*
Realize that if he's most likely kept this a secret his whole life - just doing it in front of someone will feel awkward, even if you are his wife/fiancee/girlfriend or whatever. I've been dressing in front of my wife for a couple years now (off/on... my urge to do it comes and goes with the seasons usually) and only recently did it NOT feel strange. It took me a LONG time to feel comfortable with it. So give him time to come into it. I think the trick might be to know when to push. For me, I wanted her involved, I wanted her to help, but same thing - she'd offer, and I'd decline. I was afraid I think of the awkwardness that I was convinced would follow. Really only after my wife kinda pushed me a little did I come around - and she was good about pushing, then backing off, and letting me come around to the same decision later.
I think something that helped break the ice for my wife and I: shopping. She hit up the local goodwill one day when I was at work and bought a TON of clothes (and she found some really really great, current, stylish stuff... I will never doubt goodwill again!) I came home, she had a "surprise" for me. Ultimately, the urge and desire to try on some of the things she had purchased for me outweighed the fear of the awkwardness... and off I went.

Since, she's helped me with makeup, a wig, a bunch of outfits - we've bonded over it, and honestly I still can't believe how (IMO) beautiful I feel I look when she's done with me.
Just give it time. My wife and I have a great relationship and it still took years to get to this point. Be patient, don't rush it. YOU need to be sure you're comfortable with it too - it will be pretty devastating to him if you push and push to get involved, and then when he finally lets you in, you have a bad reaction to it. Been there, done that.
Good luck!