Colorize a Black/White Image

I did two for this assignment. For the first one I picked a black and white image and used the gradient tool to color the background with red. I then put that layer at 50% opacity, and erased where there was black. For the second image I found a black and white flower, colored over it with a light and dark yellow, and put that layer at 50% opacity. Then I colored the background with a dark green.