The last color is transparency. It is #9f5b53, which in turn represents rgb (159, 91, 83).
Checking Resize Canvas so you will know the canvas in the second image too, you don't want a smaller canvas in the second image, if you do a animated texture or add other things in a second image or more
Don't forget that the image must always be gif or png for pixel art, or it will loog with smudges in a jpg file ! For Quake 2 or Quake 2 mods, like DoD, save as .jpg or .pcx file with Paint Shop Pro 7 or Gimp and then convert in .wal with Wally.