Hello @Marc-and-Bev0,
If you started the process of creating a new listing but didn't finish it you should be able to finish it as follows.
Log in on a laptop and click on "Host" and then on "Listing". Your two existing listings and the new unfinished one should then be visible as in my case in the screenshot below. Clicking on the "Finish" button should allow you to take up were you left off.
If you completed all the steps but just didn't publish it then you should be able to publish it as follows.
Click on "Host" and then on "Listing". Then click on the listing you want. Scroll to the end of the page and click the "Edit" button for the "Listing status" section. Then click in the "Listing status" box and select "Listed". Then click on "Save".
Remember to check that you've set your availablity, pricing, house rules, amenities etc. for the new listing.
Steve.