subdomains and WordPress global dashboard

Hi everyone.
I’ve had a hosted wordpress.com blog for a while and I really like the amount of traffic I get from the wordpress.com community (as little as that may be ?? ).

However I just moved over to a self-hosted blog so I can use the cool plugins and stuff. But how do I do this without losing the WP.com traffic? How do I mesh the WordPress.com blog with the self hosted blog so my post tags can show up in the global dashboard?

I mean, I know it can be done because I’ve seen self hosted blogs whose post categories/tags show up on the WordPress.com/tags list. I just can’t figure out how.

Anyone?… can ya help a WP noob out a little. (where it says “noob” please translate as: I have no idea how to write code, nor do I know techno-speak or jargon. Please keep explanations as idiot-proof as possible.)

Any ideas or advice is much appreciated.
Thanks,
Rob