There are two ways to create Tiles. The first method is to directly create a Tile Asset. The other method is automatically generate the Tiles from a selection of Sprites.
To create a Tile, select from the Project menu Create > Tile. Then select where to save the new Tile Asset.
Automatic or multiple Tile creation requires a Palette to be loaded in the Tile Palette. If there is no Palette loaded you need to create a new Palette.
To create a new Palette, open the Tile Palette from Window > Tile Palette.
Click the Create New Palette button in the Tile Palette. Provide a name for the Palette and click the Create button. Select a folder to save the Palette. The created Palette is automatically loaded.
Drag and drop Textures or Sprites from the Assets folder onto the Tile Palette. Choose where to save the new Tile Assets. New Tile Assets are generated in the selected folder and the Tiles are placed on the Tile Palette. Remember to save your project to save the Palette.