First off, visit the actual couch surfing website at www.couchsurfing.org
where you can find all sorts of people willing to host and sign up. Fill out your profile honestly and include a picture or a few (better) to increase your chances of people being willing to host.
If you're at all nervous about it, there are several things you can do to increase your chances of having a good couch surfing experience. First, surf only with verified users, who have had to verify their identity by submitting credit card information. Second surf only with people who have recommendations, and have been "vouched" for (read up on the vouching system on the site). Third, you can choose to meet your prospective hosts at a coffee shop or something beforehand to see if you feel comfortable around them (I tend to think that's a bit much, but I'm overly trusting of people).
I've had 10-15 surfers stay with me and never once have I felt unsafe. I've had great experiences hosting surfers and gotten to know some really interesting people; as a bonus, I now have a place to stay in a number of different countries should I choose to visit them.
Couch surfing is great; be safe and have fun!