To freeze bananas, you will need a few things, Wax Paper, a sheet pan, and bananas... This is what I do when they are overripe :)
Peel the bananas, and dice them into manageable chunks. I have one row sideways for you to see about how thick I cut them. Lay them on the wax paper lined sheet pan, and place the whole pan in the freezer for about 20 minutes. This helps keep them separate when they are in the freezer so you can thaw them or use them as needed.
The frozen chunks are good to throw into smoothies with other frozen fruit in place of using ice cubes. It is actually one of my favorite things to do with them.