If you're trying to install a .tar.gz file, you need to compile it in order to "install" it. Check out this "LinuxAnswers" how-to on how to decompress, configure, and install files from source:
I believe that .src.rpm files just install the actual source file which you then have to compile. Check out the how-to, it's well written and a good walk-through on how to install from source.
And if you "lose" a file in the future, you can use this (as root) to find it:
find / | grep filename
where "filename" is replaced with what you're looking for (or even a partial name like:
find / | grep lopster
Hope that helps
Sorry for "reposting" Tricky, looks like you beat me to the punch.