You want a "simple" social network with very basic functions, not much to it.
However, your wording of question says that you do not have much experience in programming, hence, don't try to do it yourself: although "simple" to develop, it is still way above the abilities of any beginner (and even some relatively experienced coders).
To get your website up and running, google "hosting services" and search a local host. Analyse their plans. Usually, they offer domain name and hosting in one package.
Look and subscribe to a server that offers:
- domain name registration,
- hosting on LAMP server [Linus/unix, Apache, Mysql and Php] (No Window, please, that would be the biggest mistake you can make (==> licence fees all over the place, average annual cost 3 x higher, Microsoft inexistent "support", bug filled ASP etc...)
- You do NOT need a dedicated server (more expensive), unless you have 1000's of visitors per day. You can always change later.
- Place a development request with rentacoder.com, web2coders.com, getafreelancer.com to get quotes for your development.
- Contract with one of the developer to do the work.
- Reasonnably expect quotes from 800$ to 2500$. (Anything below and you WILL bite your fingers - that's a promise).
Now, some warnings:
- A reasonnable social network will take 4 to 8 weeks to develop (shorter time means using free scripts that will give you troubles later), although yours could take only 2-4 weeks.
- Once on-line, do not expect 1000's of visitors per month: it takes AGES to get visitors, and depends essentially on the contents of your site. Be happy if you get 15 unique daily visitors to your site after six months, or prepare yourself to invert heavilly in advertising (not on the net, but in the local papers, radio, TV).
Good luck!