It can be, the procedural generation gives a wide range of possible progressions, and you'll see all kinds of progressions.
To take a screenshot: Depends on your system, with some variations, but the PrtScr button may well put the whole of your screen in the clipboard buffer that you can paste into any Paint-like program for editing (or perhaps straight into a file, to
open by such an editor). Alt-PrtScr likely does the same with the active window only, which saves editing time, but you're probably going to want to trim edges of anyway.
You may even want to take multiple screenshots of the DF screen, in differently-scrolled states, to compose into a larger display, but that's according to your wishes and capabilities.
Whatever you do to
get the image, and compose it to your liking, now find an image-hosting site that you can upload to and get a link to in here. There are too many possible options to list, but plenty of free ones exist, with differing approaches and vaguaries to their operation. I leave you to discover what works for you, or get more learned suggestions from others.
You use the tagging [img]http://whatever.url/imagename.jpg[/img] (click the left-hand button, second row, on the composition bar above - it's the one beneath the Bold button - to write the tag in, if you don't already have that ready to paste) to embed the image. Putting that inside a [spoiler][/spoiler] tag will make itbless intrusive, especially if it is large. Or link to it as a [url][/url] tag, with a warning, if it's very large.
(However you get to this point, use "Preview" and adjust, prior to "Post"ing, until you're happy.)