Pencilart,

sh3P files are Plug-ins
sh3F files are Furniture files
sh3T files are Texture files

If I remember correctly you are using some Linux flavour. For Ubuntu, you just put the
- SH3P files in ./eteks/sweethome3d/plugins directory
- SH3F files in ./eteks/sweethome3d/furniture directory
So I guess for you it will be the same?

The files are loaded when you (re-)start SH3D.
If you delete the files they can't be loaded, so the lights will disappear.

Maybe it's a good idea to read again what the manual says about installing plug-ins?

Hans