It is the same as most. Power Button / Volume Down simultaneously.
Some will say get a Screenshot APP.
In my case it was awkward to press them, app did EXACTLY same thing (worthless)!
But apparently certain apps BLOCK the OS from screen caps. Storage busy.

LOL, would it not have been easier to simply answer? Instead of pointing to an empty page?

How do I screenshot on my ellispsis 7

Hi sadie. A similar question has already been answered. See link below.

Link: How do you take a screenshot on the Ellipsis 7?