Well your in the right place. You might want to start by reading some stories that you think she might enjoy, then interduce those stories to her.

Or you might have her sit down beside you and read them togather. This will open up the lines of communication and if your honest with each other, it could lead to something new.

Take it so and easy, if you show up wearing leather and an carrying a whip in the bedroom without her knowing about it you just may start a fight. And like most men, you'll lose.

Attend a local munch, either with her or without your wife so you get to know the "community". She may feel that this is "weird" or "sick", if you know people that are sane and are into this stuff it may help her get over those feelings.

Welcome to the world of BDSM. Bet you didn't figure it be so much work.