Hi Anita. I’m still figuring it out, too!
With the list of publications, there’s 2 ways you can submit. First, scroll through the page and look for the green “contribute” button. When you click the button, you’ll be able to submit a post (for consideration) to that publication.
Not all of them have green contribute buttons, though. For the rest, click on the title of the publication, which will take you to the publication’s page on medium. Then look for a “submit” or “about” link with info on how to submit.
Yet a 3rd method — go directly to this page where you’ll see ALL the publications accepting contributions. https://www.smedian.com/pubs
Hope that helps! :)