have you ever used reddit? this is like reddit, you can't post directly to your profile, you have to post to a community. You can find our local communities here. You can post to one of those communities, or, if you want to create your own community so that you can post your posts there, on the same page I've linked you can see a "Created local community" button, you can mess with the settings when creating a community to limit who can post in a community.

You asked about flairs, flairs are a per community thing, they are just a little label that communities can use to help further organize posts in a community, for example !gonewild@fedinsfw.app has flairs that are used to mark the gender of the poster. You can select a flair on the page where you create a post.

I saw you also asked me where the sitewide rules are in a direct dm, so here is a link to the sitewide rules: https://fedinsfw.app/rules. Each community has it's own rules in the sidebar. When you are on the site's homepage(https://fedinsfw.app/) the sitewide rules will be in the sidebar, when you are on a community's page, you will see the community's sidebar, so you will see the community's rules.

A community's url will always be [websiteurl]/c/[communityname], to use gonewild as an example, the url looks like this: https://fedinsfw.app/c/gonewild.

Also to create a post, when you are on a community's page, you should see a "Create Post" button, which is how you create a post in a community.