tl;dr Go to https://forum.image.sc/my/preferences/tags and add your tag of interest.
I’ve had a few discussions recently in which someone was worried about missing out on posts with a certain tag. I’m not sure if everyone will see this post, but I thought I’d write up the basics for others to refer to.
If you would like to learn how to find these settings:
(1) First click on your icon at the top right:
(2) Then click on icon of the little person on the right (here highlighted in yellow):
(3) Then choose “Preferences”:
(4) You should see your profile picture now. Scroll down to the “Tags” sections of “Notifications”:
(5) The tags that you currently follow will be listed like this:
(6) Add any tag you would like to receive a notification for. Here, #ome-ngff:
Hope that helps.