First of all, an admin needs to enable it via Special:WikiFeatures.
Once it's enabled, press the "Create A Page" button and seleclt "Top 10 list". Then you will directly go to Special:CreateTopList. It has some fields:
List name- your Top 10 List name.
A short description of your Top 10 List- (exacly what it is) appears above the list and below the list name.
image- you can upload an image from your computer. If it's transparent, the background would be black, so pay attention for it.
Use the #1, #2 and #3 for your list items.
Use the "Add a new item" button below for adding more items.