you can use the yast software installation or, if you have the rpm
package on your computer, you can use the right click on the package and
choose install.
If you have a good repositories added to yast2 maybe the rpm you want is
ready to be installed. If it is not present and you downloaded the rpm
you can still install it using
yast2 -i --install <name of your package> if there are no dependencies
it will be installed. As the poster above mine says try reading it. or
man yast2
Normally, you can install an rpm by double-clicking on it (then
following the instruction… “next, next” stuff; you’ll also have to
provide the root password when asked.)
Now, popular software can be found in repositories. You can use software.opensuse.org/search to search a program and you can click the
“1-Click Install” button next to it. This will automatically handle
everything (adding the necessary repository, installing the package,
dependencies etc.).