openSUSE Linux doesn't have the “apt-get” command that users of Debian Linux and its derivatives provide as a simple mechanism to download some application that you've heard of, but don't have installed. However, it isn't hard to find most things that you might want for openSUSE, it's just that the process is different.
The best place to start is https://software.opensuse.org/. You can download openSUSE from here, but you can also find applications that you need for your openSUSE installation. In the left-hand column are the “Software” links. The Software Search link returns a list of URLs for repositories that contain the application that you want, while the other “Software” links take you to lists of repositories. In both cases, you need to add the repository or repositories that you need to your list of openSUSE sources.
To do this, start YaST, then from the “Software” group select “Installation Source” (openSUSE 10.2 or earlier) or “Software Repositories” (openSUSE 10.3 or later). Press “Add”, then “Specify URL...”, and then paste in the repository URL that you found earlier. Once you have done this, you can use YaST's “Software Management” to locate and install the software that you want from the repository that you have added.
You rarely have to add new repositories once you have added a few, as each contains many packages. So, this isn't something that you will need to do every time you are looking for a new application, but you will have to do it sometimes.
I hope that helps, if you have been looking for software for openSUSE.