How do you have Ajax requests fade in with jQuery?

I’m toying around with jQuery (without really knowing Javascript) and am trying to load another page (that’s carrying the text “Yo”) into the first page using AJAX. Now, I can do that part, but I’d like it to fade in and can’t figure out how to do that. With some help from the #jquery IRC chat I managed to have it fade in, however, after the AJAX request it’s also displayed immediately, so it’s showed twice. You can see what I’m doing at this page.

Any suggestions on how to do this (I suppose it’s not that difficult) would be appreciated :)