[Skunkworks] Wordpress blog themes

Hey guys, I know I've asked this question like a million times and I'll keep asking till someone helps me out How do I customize my Wordpress blog theme? when I search i just get instructions on FTP and stuff which of course I don't really get and can't really do since I don't have a site hence no username or password...it's just a lot of jargon Someone please answer...even if it's not possible to do so just tell me. thanks