You've already done what is arguably the most difficult part of the process which is signing up for an account on a instance and getting your first post through, so kudos!

I'll just mention that I noticed your account is on Lemmy.world so be careful about which instance you're posting to as they each have their own set of rules - there are a few where sexual content is banned entirely because it's tough to moderate. A good analogy I've found to help wrap your head around things is to think of it like email. You can have your Gmail(Lemmy.world) account and it will have it's own set of rules, features and communities, but it can talk to and post with an Outlook (lemmynsfw.com) account which also has its own set of rules even though they are two separate entities. The whole concept is weird at first, but you'll get used to it pretty quickly if you stick around.

The communities themselves are a lot smaller than you may be used to if you post on Reddit, for example. Be a bit more mindful of spamming since there's a smaller number of posts overall. Otherwise I've found the people around these parts to be very friendly and welcoming.

I noticed your other post mentioning some technical issues. There isn't an official Lemmy app (unless maybe you count Jerboa) so it may be best to check the community dedicated to that app for more specific details.

Edit: I kind of figured because of the user watermark, but I saw another comment confirming you came over from Reddit. One specific thing to mention if that's the case is that there isn't any form of Karma system in place. Upvotes and downvotes are purely used to indicate post quality and fit to the community and impacts feed sorting mostly. That doesn't mean people won't use it as an I don't like this button though.