Rules can be found here
What do you mean by "understanding which categories are?" The categories of the different topics are shown on the front page of the site, if that's what you mean.
Well, when i see the different categories, they don’t really have a description i can see, so im not sure if /you/ is just a general forum or if it’s something else entirely. Most of them i can speculate what im supposed to post there, but i just wanna see a description just in case.
Sorry, I didn't see your reply very quickly. There aren't descriptions for them, but yeah, /you/ is just a general chat board for random topics, /jrn/ is talking about stuff in one's life, honestly the rules for posting on a particular board aren't strict at all, just post something where you think it'd go.
im completely new. Only reason i joined was because i wanted to join 4chan because i thought it would be a cool place to be with a bunch of funny stuff, but i heard it has gore and scary stuff. So i thought this is a more tame 4chan like place.