Color the butter cream is easy! Fundamental is the kind of dyes to use: I recommend those in the gel, as it does not alter the compound. Another piece of advice that would give you is to not go overboard with the color, rather than adding it in small amounts so as to choose the shade that suits your needs. If the color obtained is too strong for your taste, you can add more butter cream to lighten.
Add divide the buttercream into three parts and put it in three different containers. Gradually add the dye and stir well from the bottom to the top.
So you will get the desired colors. I used the red to get pink, blue to blue and blue to get more yellow green.
Place the cream the butter with a pastry bag, using different nozzles to decorate