It's very confusing!! I am currently paid to Godaddy.com for the domain name, then Wordpress.com to host the blog site. I want to change the theme on the blog site, so I just downloaded FTP from filezilla.com. Here is the question: after I opened filezilla, I need to put in "Host", "Username", "Password", and "port"..I tried every one of them, but didn't work. So do I enter Godaddy.com or Wordpress.com on "Host" section? and how about username, password and port? Please help. Thanks

Not sure it is possible. Wordpress hosting seems limited. Further info found:

http://wordpress.org/support/topic/12812...