Add button to add items to a list in a Fragment

I made an app that has 3 different tabs with 3 lists. My question is how I can make a MainActivity button or a menu one that can add items to the specific list for the selected tab. I know how to make a list on a simple layout, but I can’t figured it out how to make a list with the add button function în a fragment ; I searched a lot but still … 🙁