How to annotate a game?
Well I’m not on a computer so I can’t do that but you can manually type the text into the PGN like this:
{POTATO}
Go to "analysis" and insert your game:

Right-click on any move and choose "Comment after" or "Comment before":

Write your comment:

Thank you for this. I had thought that only Masters with expensive equipment could do this.
Regarding the "insert your game" part, what is the best way to do that?
I know how to insert the game to the board but don't know how to annotate
Help please
Start by studying the game until you comprehend the critical moments and themes.
If you want people to take you seriously, make sure you post with White on the bottom.
Thank you for this. I had thought that only Masters with expensive equipment could do this.
Regarding the "insert your game" part, what is the best way to do that?
You can post games/puzzles with a web browser (not the apps).
https://support.chess.com/article/316-how-do-i-put-a-game-or-puzzle-in-a-forum-post
Is there any downloadable software (for Mac) that can do the same thing? I've tried with Stockfish, but it doesn't seem to accept any insertions.
For the Mac, you should look into https://www.hiarcs.com
More choices are available for the PC. I’ve been using ChessBase software for twenty years. It has kept me from buying a Mac.
I know how to insert the game to the board but don't know how to annotate
Help please