Ok, i'm using photoshop to make textures. Now i made some hand trails with a transparent background and a picture on it (saving it as .tga ofcourse). Now it would be logical that i can only see the picture as the trail, but no.. the background turns white!

How do i make it so i can actually only see what i want to see?

have u put ur shader on

Yes.

Heres a picture..

Save it as png instead, i dont think tga supports transparency, just add an alpha channel, etc.

Have you ticked transparent textures in the options menu?

I've put transparency 1 in options menu, yes.

If i save it as png, i can't preview it by putting it into the custom folder and typing "/lp 0 foldername" ingame..

make black background in alpha channel

For toribash, you need to use channels to make transparency.
Here's a tutorial on that. (by me)
http://forums.toribash.com/showthread.php?t=36689

Thanks a lot, got it now : )