To hang garland on a Christmas tree, you will need to first gather your supplies. You will need a roll of garland, some ornaments, and some lights. You will also need a ladder, if your tree is tall. Then, start by wrapping the garland around the tree, making sure to cover the entire tree with the garland. You can start from the top and work your way down, or start from the bottom and work your way up. Once the garland is wrapped around the tree, you can add the ornaments and lights.