The easiest way to install Linux SW is with the package manager--it is accessible from your GUI menus. The package manager goes to a repository on the web--or perhaps also to your installation CD or DVD.
The process with a package manager is typically seamless---ie you select the SW, click "install" (or something like that) and you're done.
If you want something that is not in the repositories for your distribution, then you have to work just slightly harder. The first thing to do is try to find an "rpm" package. (I hope I am remembering correctly that SUSE uses .rpm)
Assuming that you do not have dependency issues, then installing an rpm package is easy. Using the terminal:
Unzip and unpack: Packages will come in two common forms: .tar.gz and .tar.bz2 The corresponding commands are:
tar -zxvf <filename>
tar -jxvf <filename>
Now you will have a folder with at least one file ending in .rpm. In this folder, type:
rpm -i <filename>
If--after trying it a few times to build confidence--you find this too hard for your target users, then you will have to stick with package managers. With some distros I have tried, there is almost nothing that is not available. In many cases, you can find the repository index at the web site for the distro.