Just download Firebird from http://www.mozilla.org/products/firebird

The Linux download comes with a version precompiled for i386; Just download it to your home directory, open a shell prompt, and type the following series of commands

su root # enter your root password when prompted
cp MozillaFirebird-0.7-i686-pc-linux-gnu.tar.gz /opt # you should use Tab Completion to avoid having to type out the full filename
cd /opt
tar -xzvf MozillaFirebird-0.7-i686-pc-linux-gnu.tar.gz
exit
exit
Now, on your desktop, create a shortcut (Link to Application) to /opt/MozillaFirebird/MozillaFirebird

No rpm needed, no .configure/make/make install needed, just unzip and run as easily as though it were a Windows program. (Yes, you *can* just double-click on the .tar.gz file in your home directory and unzip it to /opt/MozillaFirebird if you like, I just prefer the command-line)