Here is the best simple, but effective, set of instructions for using this forum (a Discourse forum) that I have seen:
Thank you, @JMichaelTX for finding that post and putting a link here.
(And I’ve just clicked the bookmark icon for your post. )
Reminds me, yet again, how rare is attitude of helpfulness on this forum, compared to most all other Internet forums.
###How to Use the Shortcuts for Post Actions
Before you can use some of the Post Action shortcuts, you must first select the post using the J or K keys.
The selected post is identified by a red bar on the left side of the post, like this: