Discord has a lot of bells and whistles, so it's totally normal to feel a little overwhelmed, even when you're fairly certain you're in the right channel. They make great use of emojis and stickers and gifs, and you can learn more about those kinds of things in this article from Discord.
However, our rules state that in the #star-trek-picard-s3 channel, you must use spoiler tags if you wish to discuss the latest episode prior to midnight, Eastern Time (GMT/UTC-4) on Sunday morning, which is to say midnight between Saturday and Sunday. So how do you do that?
You'll use a special kind of formatting called Markdown, which has a spoiler tag available. If you use two pipe characters ( || ) in your text, that will hide your text until someone clicks on it.
Example that spoils nothing from Picard, I swear: Oh wow, I just saw episode 3 and || I can't wait for episode 4 because of what Commander Shelby does! ||
So everything between the two sets of pipe characters ( || ) will be hidden from view until someone clicks on it. This will then reveal the text. You can read more about spoilers, including the "easy" way to mark something as a spoiler, by reading this article from Discord.