I have a lot of thoughts I can share, Ivy, but I'm not too sure which ones will be most helpful, so I'll just toss a few of the thoughts on top out, and if you have questions, just ask me further!
First, to answer one question, I read and reviewed the Mistress Manual, and from my perspective as a naturally submissive sort of person, it was geared more toward people who already have an innate knack for dominance that they're trying to focus, and not so much for people who were coming from a place of not understanding very much yet. I did learn a fair amount of useful ideas for building a "scene," and what some driving factors of men's desires for submission can be... but in terms of making me feel more comfortable, it didn't do a whole lot. It also did tend to focus a lot on things that I identified as more like "humiliation/degr adati on" than simple S&M, and humiliation is a turn-off for me (both giving and receiving.)
But, on the other part---I think Diabolical Kitty makes a good point about the differences between being Dominant or Submissive vs. topping or bottoming. No matter which way (or in the middle) you're naturally aligned, it's possible to put on a different hat for sex occasionally in order to give your partner something that they would really appreciate. And, in most cases, people learn to enjoy topping/bottoming for the sake of it eventually too.
I have a friend whose personality is pretty similar to mine, and we were lovers several years ago, and the sex was fabulous but not particularly exploratory, because we both like a partner to lead. We didn't have sex for a few years, but then got back together again, and he easily leapt into a totally new role. (I had learned to be more vocal in the intervening years, so I asked him to slap my ass---and he immediately did, perfectly, and then went on to call the shots for the rest of the session.) And then afterward reverted to his normal self, and said basically "see? Learning to top can be kind of fun!"
I'm going to interject a little bit here about the motivation for wanting to be dominated. In my case, I have a strong innate desire to know that I'm making my partner happy, and I feel like I can do the best job of that when my partner's telling me exactly what his desires are. It's also nice---I have a pretty dominant personality in some areas of my life---and if you look up Dan Savage on dominance, he says it's pretty common for people who are always having to make decisions in high-pressure jobs to want to have one aspect of their lives where they are released of control. Letting someone else call the shots can be relaxing and freeing.
And then, there's the part where "it just feels good." I actually went to visit a Pro Domme once, out of curiosity. She was super kind, gave me the cheapest rate she charged (it's not very often they get girls, I guess), and happily explained everything she was using, how it was made, and how it would feel, before she hit me with it. She spanked me, flogged me, cuffed me up in a standing position and whipped me, and then let me go. (There wasn't much "scene" to it, because I was there more for curiosity than for "release.") But I left feeling like I'd just gotten the most skillful full-body massage. A nice suede flogger does wonders for knots in your shoulders, apparently ---and I did leave with plenty of bruises, but she made a point of asking frequently "is this too much, not enough, or the correct amount of force?" So despite being bruised, I felt wonderful.
And, for my part---I am submissive, but I've never really been attracted to naturally dominant guys. Maybe this will change as I'm actually starting to get to know and understand myself better---but instinctively, because I know my personality is soft and trample-able, I'm usually afraid to get very close to people I know could take advantage of that. So I've wound up coupled (in medium to long term relationships, at least) with other submissive types, typically. This might explain a bit about why your husband likes you so much---he can see the dominant parts, and be thrilled that he's with a brilliant and strong woman---but instinctively he knows you are very kind and caring, and would never do anything to push him more than he could bear, or actually hurt him. So be flattered by that!
So, as far as doing it---when I had a partner who liked being pegged, it was really easy for me to flip into "top" mode, because there was a very visible cue that I was "supposed to be in charge." And I just had to remind myself, "he wants me to be confident," and when you're just starting out, start with simple things like telling him which position to be in, where to lick/worship/whatever your body, or telling him not to cum yet, or yes cum now. If your husband is not into being pegged, you could probably convince your brain to respond in a similar way---when the cuffs are out, you're in charge. Or something similar.
And, when you're starting new things---once you take off the cuffs (or whatever else), spend a lot of time cuddled up with your husband. If he wants to talk immediately about how much he liked it, have the discussion then. If not, talk the next day. But cuddle a lot and reestablish that your relationship is still the same no matter what gets explored during sex. Everyone talks about safe words, few people recommend that for new BDSM players, but I think it's important.
Okay, that was a full essay. Let me know if you have more questions!