2 problems,Please help

Hello every1
I’m kinda noob in WP so I have a little problem

1.

So I installed my blog here:
http://sethworkz.comuf.com/
and a page of it looks like this
http://sethworkz.comuf.com/?p=39
If I change the permalinks to this:
http://sethworkz.comuf.com/2010/01/23/sample-post/
Then the server gives me an error message.
How can I fix this?

2.

The second one is about my domain.
I haven’t buyed a domain,I just use dot.tk
They have a new thing activated.
Dot.tk free domains can be used as parked domains now.
Okay.
I added the two nameservers of my host at the dot.tk.
Ok.
I parked my domain at the CPanel of my host.
My problem is that if I acces the site from my domain which is:
http://www.sethworkz.tk
it works,but the links are still pointing to sethworkz.comuf.com
How can I achieve so that be like this:
http://www.sethworkz.tk/?p=39
or
http://www.sethworkz.tk/2010/01/23/sample-post/
If I navigate with the browser here:
http://www.sethworkz.tk/?p=39
it works,but on the blog,the links still pointing at comuf.com
Please help me.

Mail me or something: sethpda@live.com

Thanks