Are you familiar with the FPS Creator 'files' folder? ie: Do you know how to open your box's fpe. file? If not, then go to C:\Program Files\The Game Creators\FPS Creator\Files\
entitybank and locate your box. Open the fpe. file and you'll see a line called
textured=. You can now do one of two things, the simpler being the first one:
1) Paste your texture file in the
same folder that your entities fpe is in. Let's call it 'box_tex'. Let's also say this is a jpeg image. Go back into the fpe and insert this in the 'textured' field:
box_tex.jpg
2) Let's say your texture is in the texturebank in WWII media. If you don't want to do the above, you can refer to the texture in your fpe. You know that 'textured' field? You'll be required to paste the location of the texture on your hard drive. Example:
textured=C:\Program Files\The Game Creators\FPS Creator\Files\texturebank\ww2\scenery\furniture\box_tex.jpg
Hopefully this doesn't sound complicated. It will become second nature in ten minutes.
If it feels good, it's a sin.