How do I populate a multisite site?

I want to use one userbase for my three wordpress sites. I already have them setup, without multisite, in different directories. I found out from the folks on wpmdev that I should use multisite so I'm switching. I turned the network on. It defaulted me to using subdirectories... im ok with that. But when I create a new site nothing gets popuplated into the site. I added the subdomain using cpanel. How do I get it to actually setup and populate the site so I can assign a theme, etc.?

Main site: http://www.sozocial.com
site that I'm adding as subdomain http://community.sozocial.com

A related question... http://www.sozocial.com/learn is my third site... if I set that one up for multisite I need to create the site in the network, and i've already done the subdomain in cpanel. HOw can I export my currently setup http://www.sozocial.com/learn and import into my new multisite site at http://learn.sozocial.com? What's weird is that i setup the subdomain and it's pointing to the learn site... ugh, this is confusing. I hope I didn't jack i all up, I would really not like having to redo the site. hah! thanks.

thanks