[Need to do Color FIll]

Hello, I have created an image - triangle within a rectangle - using a grid (to keep my lines straight), and I wish to fill in each horizontal "grid line" with different colors.  I cannot figure out the fill function.  It gave me "two dots with a slide", but no color was filled into my selected row.

What am I doing wrong? and how do I save my different colors for future use? 

I also want the colors in the horizontal rows of the triangle to be different than the background rectangle and its colors.