Bart,

Do you know how to install plugins in general? There is your answer.

Using your FTP client you upload the "tidypics" latest release into the MOD directory.

Once uploaded to your server it should show up in your "tool" list. Enable "tidypics".

This is standard for most plugins. Then there are some customizing options once enabled. Talk to your server company about GD versus Imagemagik etc. They should be able to help, but the GD should work without any special help out of the box.

Good luck!

TahoeBilly