You have to make a new folder in the /custom directory and call it "tester" or something.
Save the textures in there as a .tga.
Open Toribash, click on freeplay then type /lp 0 tester.
The textures should be there, if you didn't check RLE Compression (if you're using GIMP).

I hope I helped.

Notice this works with every member of toribash also...
If you have their custom folder you can always type /lp 1 [name of player] or /lp 0 [name of player] without brackets.
If this doesn't work, you may not have their custom folder..
For this type /dl [Name of Player] this is to download their custom folder, then type /lp 0/1 [Name of Player]. Notice it's either 1 or 0, not both with the / in between.
If you still need more help with this, fell free to PM me.