Hehe, this is going to be a looooooong post.
You can start with some brushes. One of my favorite sites is http://celestial-star.net You then go to File>Import>Brushes (or something like that) And Select the brush. Well, first you'll have to paste it into the My PSP Files folder under My documents? I believe. Then, you import it as I said above. For fonts, http://dafont.com is great. You'll have to find your font folder, extract the font from the folder it came in from dafont.com, then place the font into the font folder. For backgrounds I normally make my own with brushes, but you can also get some from http://hybrid-genesis.net It's been a long time since I've used PSP, but there's a little bit of information to get you started.