re: Help - first time cake decorator now thinking I can't do what I want to do!

Are you covering your cake in icing or fondant. Two different mediums. If you stick to bright colours, using gel colour, not liquid colouring, they will show up well on the purple. Use yellow, orange, pink, light green..and make as bright as possible.
Hope this helps.

Creativity is God's gift to us. Using our creativity is our gift back to God. Clarky's Cakes 😎