First thing you'll have to do is buy your domain name. You can look up and purchase domains at sites like namecheap.com and godaddy.com.
Second, get yourself some hosting. You could always get a bundled hosting package with your domain at godaddy, but they tend to rip you off. Hostgator.com is a good company for cheap reliable hosting, but you can probably find a smaller hosting company that's even cheaper.
Third, decide what you want to be included in your site(forum, store, blog, etc), it might sound dumb, but make a map of your site on paper, it gives you a better idea of what you're gonna have to get.
Lastly, if you know a little bit about HTML, CSS, Flash you can get software like Dreamweaver and build the site yourself, but if you don't know much about the previous mention items, you should probably freelance the sitebuilding. You can find a good site designer almost anywhere on the internet, but check freelancer.com for cheap ones. Also, sites like wix.com make building a amazing flash site easy, but to use the site you build with them you have to pay for their hosting plan(which is pretty overpriced).