Usually people request to contribute to PoetsUnlimited by tweeting to me, the editor @ottaross — but your post worked fine too as you’re not a Twitter user.
So — mission accomplished. I’ve added you as a contributor. Now if you create a poem as a “New Story” in Medium, you can submit it to PoetsUnlimited, and I can accept it into the publication. Sometimes the buttons on medium seem a bit hidden for new users. Look for what you need typically in the top right, or bottom right (the … button) on the page.
FYI — another way for people discovering PoetsUnlimited to contact me (or anyone who has created an article, story, poem etc) is to highlight a bit of text, then click the ‘pen’ icon to make a note. Anything that works.