Double-click to select the face to which you want to add the material, and then select the material.

If you give a map, choose a color that is not used in the model, otherwise the material of this color will be covered by the map.

Edit-Use Textured Pictures

Find the location of the picture, select the map, and the tiles on the picture are ready.

If the size of the map is not suitable, you can manually change the size of the map yourself.