Is there any way I can add my own textures in NetRadiant? I'm looking to do this because I want to have a green screen in-game for my films. 
Please search. If you can't do that then make makes a folder called "mymap" or whatever you want to call it, in the tremulous base/textures folder and place your textures in the "mymap" folder.
I did search. Couldn't find anything, but I will do that. Thanks.

Edit: The texture files are .tga How do I convert my image to that format?

Edit Again: Ok I converted the images but when I open the .pk3 and try to insert them with WinRar, it won't work. I'm trying it with another program.