bejadus, I agree that you can't 'drag' someone into bdsm... they have to want to try it themselves. I agree with the above posters that you need to sit down and talk to her.
Ask her about how she feels about bdsm... ask her if she even knows what it is. Some people think 'omg! bdsm! like bulwhips and chains and stuff? no thanks!' but they don't even know that bdsm can be as simple as a scarf to the headboard or a blindfold... you don't even need props like maybe you like to talk and do the more 'mind game' like stuff.
For example, my Dom likes to hold my wrists down during sex and tell me "this is your life now, you're just my little fucktoy..." or clapping your hand over her mouth so she can't talk... lots of 'softer' stuff can be done as a sort of introduction. Also everyone likes such different things, she might not like any of the above suggestions.
Ask her how she feels about you spanking her? Tying her up? don't do some intricate Japanese rope bondage, just tie her wrists together and hold them while you have sex... simple stuff and take it slow.