If you're logged in to lemmy.world, I think you can click the hamburger menu top right and then "Create community"?

Edit: sorry, just noticed your account is on programming.dev, where there's no such option? Then I'm afraid I don't know :/

Edit 2: From the programming.dev sidebar:

Community Creation

Communities in our instance are created from our community request zone. If you have an idea for a community that fits our instance that hasnt been made already feel free to create a post for it there. Communities will be considered for creation if theres enough interest in the idea shown by people upvoting it

In programming.dev we have a community request zone at !community_request@programming.dev

You can find info like this in the sidebar if youre on web (and there's going to be a support site made soon)

Lemmy instances can enable an option to prevent non-admins from creating communities, so if it isn’t available on your instance (usually in the header area on the website) then your instance admins have disabled that option