Not sure what fatrat is, but if you downloaded it from firefox, I belive it
is Cntrl + Shift + Y to bing up the download dialoge box. You can then
right-click on the file that was downloaded and select "open containing
folder"... Also you can bring up the dowload box under tools menu, if that
key combo doesn't work for you. If you downloaded some other way... well...
try again and note where it gets downloaded to, or else go to gnome menu
Places -> Search for files, and type in the name of the file you
downloaded. If this is a compressed file, you will have to extract it, use
the terminal to navigate to that file created when you extracted, do
./configure, make, checkinstall (or makeinstall) to install it. check
install is best so you can also cleanly unistall it.