Look up at my edit for a better link.
As for tying up your girlfriend, this can only be accomplished by mutual trust. Termed "love bondage", it's the ideal of all bondage. Depending on the level of trust, you can persuade her into bondage, but if you do persuade her, start small: wrist tying, spread-eagle tied to bed, crotch rope. This can be combined with a light cleave gag and/or blindfold. The advanced stuff comes later bro.
edit: Also, before getting into bondage, have a look at a wiki Bondage safety article: http://www.londonfetishscene.com/wipi/index.php/Bondage:_Safety
The most important thing about love bondage is that your partner feels secure in her restraints, and totally trusts the roper. Safe words are a must because if there is real physical discomfort, you need to know as soon as possible.
Umm... Thanks again. I don't know but it sounds like your worry or serious or something. It could be just me, but you don't have to worry about anything cause I am safe kinda guy. If you are not worry at all than sorry about the mistake. And thanks again