This is a large topic.
Here is an outline:
1: Place new textures in a new folder.
2: Use the Library manager to add this folder to the Archicad Library
3: RELOAD the Library
Now, textures are available for use.
4: Open the Material Dialog
5: DUPLICATE the material
6: RENAME the material
7: In the Internal Engine mode, add and size the texture
8: Specify the Alpha channel effects
9: Switch to LightWorks Engine mode
10: Click "Match with Internal Engine" to bring the texture into LightWorks renderings.
Dwight Atkinson