analytics and code in general

I have a wordpress blog here: http://www.tomtolkien.com

The blog is hosted on wordpress, not on my server.

Question – how do I add analytics code. I have upgraded to custom css but can’t find anywhere appropriate to paste the code.

Is this only available on self hosted options. If this is the case, is it possible to transfer a preexisting blog, or would I have to start again?