Changed my '.wordpress.com' to '.com'-HELP!!!

Hi,

I made blog xyz.wordpress.com.. They offered me ‘xyz.com’ domain for $17 per year. I purchased it. Now it is xyz.com but in admin panel all features are same as they were for .wordpress.com .. like I can’t upload new theme. No plugin Option.. etc ..

How to fix this problem.. Help please.. I am very upset! ??