Okay, try painting GMAX aircraft first. You only have to paint one version of day textures and FS will generate night textures for you using a lighting file. If you paint a FSDS aircraft, you have to paint both day and night textures, plus flip overs of both. I'll start off telling you how to paint the POSKY A330.
1. Download the POSKY Paint Kit of the A330
2. Open a332fuse1and2_t.bmp with ImageTool (DO NOT TOUCH THE l.bmp files! THEY ARE THE LIGHTING FILES)
3. The Paint Kit is in 16bit format. Convert to 8bit, 24bit, or 32bit for Photoshop to read it. If you convert it to 32bit, save it as a .tga
4. Open the file in Photoshop. Do your repaint. Save it.
5. Open the file in ImageTool. Convert to 16 or 32bit (without tga format).
Then repeat for all files needed to be painted.