To make yellow color, you can mix equal amounts of red and green paint together. This will create a basic yellow color. If you want to adjust the shade of yellow, you can add more of one color or the other to lighten or darken it. For example, adding more red will create a orange-yellow color, while adding more green will create a yellow-green color. You can also experiment with mixing yellow paint with other colors, such as blue or purple, to create different shades of yellow.