i tried but i don't know to make it get in the post. it would be way easier if there was an option that allowed me to attach it from a chosen location but nope, there is no such feature.
Unlike some forums, this one isn't configured to allow "upload as a attchment" to space on the forum server itself. If you can upload it to an alternate upload-holder (there are countless image-hosting sites out there, with good and bad bits to each) you ought to be able to use the imagegtags (e.g. [img]external.site.url/imagespace/abdefg.png[/img] - or similar) to include it. Some sites prevent cross-site embedding (they like you to visit their site 'properly', for various reasons) so you could just include the URL.
There's specific file-sharer site used for Dwarf Fortress on
http://dffd.bay12games.com (Dwarf Fortress File Depot), but I'm not sure about its policy on not-DF-but-still-Bay12 files. Just letting you know for next time you're stuck in DF itself.
Version-wise, the (off-Bay12, not ToadyOne any more) latest versions of LCS are version 4.12.4 or later. Elsewhere in this Curses area there are threads dedicated to these that will point you to the right place to get these versions flr various platforms, hopefully yours included.
Noting that (on the version I've just tried) possible options are (light) grey, unusable ones are (darker) grey, when not otherwise highlit, it'd be nice to check that. Also, it's keyboard-only, in case you were clicking the mouse on the text, fruitlessly.
Probably not your issue, in either case, as the point you're stuck is past numerous other necessary intersctions, but just mentioning it while I'm here.