Just unpack the file .tar.gz. In kde's konqueror you can click the right button and choose Actions > unpack here. This will create a new dir, which is the source tree of your printer driver. The dir should be called some like "driver.gimp-print-5.0.0-beta1".
Now, open a console. Go to that dir and see if there are the files readme or install. These files should give you info on how to do things. These commands below are quite standard, and should compile and installl your driver, with minimal effort.
Issue the command:
then su to root and do:
Post again if that fails.