When you are reporting or otherwise communicating around a problem you have encountered with your computer, it is often useful or necessary to include a screenshot or screen recording in your communication, to clearly communicate the apperance of the problem condition.
To capture an image of your screen contents, press the Print Screen or PrtSc button on your keyboard. The screenshot will be saved in the Pictures folder within your home folder.
Alternatively, and for more options, you can launch the Screenshot app from the desktop or desktop search bar.
To record a video of your interactions with Endless OS, press the Ctrl+Alt+Shift+R keys. You will now see an orange on the right side of the taskbar, indicating that the screen recording is happening.
When you wish to finish recording, press the same key combination once more. The video will be saved under Videos in your home folder.