Karin,
The question you ask is more complicated that you might think.
I have been trying to ease my husband in that direction for a while but he has no desire to be Dominant. Now if your husband actually has a desire and you have offered you submission to him on a silver platter, I think he will move on from there.
Here are a few things that might help.
Look up a BDSM inventory or checklist. Spend a night each checking off what you are interested in doing, what you are willing to do and how much interest you have in said activity. This will give you tons to discuss. We found it very rewarding.
Also discuss safe words with you husband. I think one big hang up with life partners is they feel they are not supposed to hurt you or they are worried they will lose control and go too far. If you have a safe word then he could possibly feel a little more relaxed about proceeding.
Be sure he knows as much as you do about your current limits. If you get to play, your limits will change but you can't know how when or how this will occur until you get to play and try things.
If you are into pain. Call it sensation and NOT pain unless HE is clear about being into giving you pain.
If you have bruises or other lovely mementos later that you enjoy, don't talk about it still hurting unless you are sure he will be happy to have marked you and hurt you. (This can scare off men who don't want to hurt you.)
If he does something you don't consider to be what you want, remember you are putting him in charge, so tread gently unless he is going past your stated limits and/or ignoring your safe word. Men are so often like little boys, if you express the slightest dissatisfaction they will sulk and find a new game to play, possibly with a new toy.
If he does something you like act like it and later shower him with praise. "Oh honey! I keep thinking about how you grabbed me the other night and just took me, doing what YOU wanted to and it makes me so happy, I'm dripping right now." Be honest though, you have to have really liked it and really be dripping. Make him feel and verify. *winks* Which brings us to...
Tease, tease, tease him. Don't let an opportunity go by in which you are not teasing him and making him simmer. Keep the anticipation up. Prime the pump.
Finally, talk and act like this is a great adventure you can talk together. It is. Each new activity is a wonderful ride. You might find you don't like the Tea Cups (figging). You might find you prefer the carousel (spanking). Whichever, just enjoy the rides as you both learn what you like and good luck.
Fury
Please note: The above is advice from someone who hasn't got a huge amount of experience herself but she's working on it and means well. Take all advice whether asked for or not with a grain of salt. Mileage my vary.