SuSE is an rpm based Linux distro. That doesn't mean that it can use rpm's from other distros, though. When downloading rpms, try to get versions for SuSe 10.1. Rpms install in much the same way that windows .exe files. From within your file manager, left click on the rpm you want to install, and you will be prompted whether or not to install.
You can also go to the main menu, click on Control Center -> YaST2 -> Software -> Install and Remove. Click on the Administrator button, then enter the root password (root is the system administrator, that's you, as opposed to you logged in as normal user). Enter the root password. In a few seconds, a screen comes up. In the top drop-down list box, click on the down arrow, select Package Groups. SuSE loads a database of all the software on the installation media, and which are currently installed. Scroll down to the bottom of the Package groups list, and click on ZZZall to get the full list in alphabetical order. Click once in the box on the left to select software to install. Click on the Accept or Apply button on the bottom right, and you will be prompted for which cd/dvd to put in the drive (from your installation set).
You will also come across .src.rpm files. They are source code files which have to be compiled into installable binary rpms which then can be installed normally.
Tar.gz files are compressed (with the gzip utility) Tape ARchives (tar). They are usually source code files to be compiled. Occaisionally, you will find one which is a binary which only needs to be untarred to give a runnable application.
There are other package formats used by other distros, such as: .deb, used by Debian and derivatives; tgz, used by Slackware and derivatives.
For all things Linux, www.google.com/linux
is your friend. Use it to research questions, search for howtos and tutorials, etc.