If you do not yet feel comfortable using Linux, then perhaps you better first read the page Working with the Shell and train a bit with the shell/terminal environments, so you can have a better perception of the steps shown in the pages for each version.
You can follow either one of these instructions:
- Follow the official instructions for building from source code: OpenFOAM Source Repository
- Or by following the detailed step-by-step instructions provided in the following pages...
Here are the openSUSE versions for which the community has already written step-by-step OpenFOAM-dev installation instructions: