How to use a checker texture in blender 2.8?

If you mean a checker pattern texture you can do the following:
1. Import your tree model
2. Mark it and go to edit mode and open up "UV/image editor"
4. Make sure your model or the desired polygongroups are selected
5. In the UV editor's menu choose "image" -> "open image" and load your checker image

What exactly do you mean that "they are organized by a texture checker"? can you send a screenshot or provide me with more explanation?