Jordie's dashboard

I just made a Tumblr page, and so far im loving the idea.
But theres just one problem, how can I change the text? Diffrent fonts, sizes, overlapping, ect. Ive seem other Tumblr blogs this way, like this one,http://ooiseau.tumblr.com/
Ive tried the HTML edit but "normal" codes wont work. What am I doing wrong?