Build membership in Social Networking Site

I have a relatively new social networking site (myspace clone). I currently have about 500 users which I acquired mostly through ads posted on Craigslist. Membership in the website is free. I would like to boost my membership to 10,000 this summer, and then on to 25,000 and to 100,000 within a year. (Obviously, more members would be better, but I'm trying to be realistic.) I am looking for someone who has experience doing this type of work. Please give me a layman's (non-technical) description of how you will go about accomplishing this. Please only bid if you have references and positive feedback. I expect this to be ongoing work, so you should probably bid a price per month. My website targets a huge and untapped market. I think there is a lot of potential for growth. I am not interested in any techniques that will get me blackballed or banned by any of the search engines.