...by pressing shift+enter
and you can also edit or delete your comments by hovering over the top right corner of them (a little pencil icon will appear). Those only work on desktop, though, not on the App.
Also to check your notifications for posts from creators (it's usually where we tell if we have to go on hiatus, are late to publish a page for some reason, if we're streaming on Picarto or such service, or any other news)
It's also where you'll be informed if an episode was updated.