Trying to make brown food coloring

It's simple color combinations. Your primary colors are red, yellow and blue. If you mix two together you get the secondary colors of orange, green and purple. Mix any complimentary colors together and you will get brown example red+ green or orange + blue...... I promise. I oil painted for many years, the sample principle applies. :)

Hi Lacey, try using a 1:1 ratio of red food coloring to green food coloring. You can use a few drops of each for a very light brown or increase the amounts for a richer, more saturated color. A (optional) very small amount of blue food coloring can help make a cooler-tone brown.

Please note that food coloring typically gets darker as it dries. I'd suggest allowing your icing to sit for 10-15 minutes to have a better idea of what the final color will be. Best of luck!

Lacey - see if this helps:
https://www.wikihow.com/Make-Brown-Food-Coloring