The way I do it is take pictures in game, and then put them in my photo album. Then, if you are in full-screen mode, hit Alt-Tab to get to your desktop again, and go to either
Start > All Programs > Microsoft Games > Zoo Tycoon 2 > Zoo Tycoon 2 Profiles
OR
C:\Documents and Settings\(Your Name Here)\Application Data\Microsoft Games\Zoo Tycoon 2\
then click your name or "default" to get to your saved games/photos. Then go to "photos" and the pics you have just taken will be in the newest album number (assuming that you have saved the pictures to your most recently created album). For instance, I have 15 albums, and my newest pics get put into folder "album15". Then scroll through, find the pictures you want to upload in there. From here you can do two things:
1. You can put it into an image program (paint works) to edit off the black edges or to resize, resave it as a new image name, and then upload it -OR-
2. Upload it straight to photobucket or imageshack.
The way file hosting sites work is this: You go there, register yourself a name, and then afterwards, you should be able to hit "Browse" to look for an image to upload from your computer. Once you have found the image you want to upload, select it, and hit "Ok" or "upload". THe site will keep a copy of the picture that is on your computer and put it on the web. That's right, now you're work is on the internet! Hooray!
If you need additional assistance, again, don't hesitate.