I am looking for assistance with installing opensuse on virtualbox on my mac. I am very new to all this and have enrolled in a system admin course which is requiring me to do this. So i watched a video and successfully installed virtualbox. unfortunately, i cannot install opensuse correctly. I downloaded it and created a file on virtualbox but when I press start to initiate the installation, I get an error message that reads: Error… no bootable medium found. system halted. I have no idea what I am doing and cannot figure out how to fix this. I am hoping someone out there is familiar and can walk me through this. Thanks.
Hi and welcome to the forum 
All you should have to do is download the iso image, then check the sha256 sum to make sure the iso image is good.
I’m guessing the file you mean is a vm file for the installed operating system to live (virtual disk), then in virtualbox you just add the iso image as a cd/dvd file and boot from this. There should be a wizard tool to perform all this in steps?
Adding a few details to Malcolm’s remarks.
Start VirtualBox, click “NEW” and create a new virtual machine choosing “Type=Linux” and “Version=OpenSUSE (64bit)”.
Stick with the defaults, or possibly enlarge the RAM from 1024 to 2048 MB (or more if your system allows…) and the virtual disk from 8 to 15-25 GB if you plan on installing a lot of additional stuff.
Create the machine, then in the machine overview, “Storage” section, click on the “empty” virtual optical disk and “Choose Optical Disk File…” pointing to your downloaded .iso image.
Start the machine, with the default settings it should boot from the install DVD image; if not so, press F12 for a boot menu and choose to boot from the CD/DVD.
Then install openSUSE to your liking. Then you might choose to change the “boot order” in the machine’s “System” section to automatically boot from the virtual hard disk, bypassing the DVD.
Enjoy openSUSE!