Hard to help you when there isn't alot of info in your post.
First: how much did it cost you to make your cake? Box mix or scratch? Consider your time and effort and what it is worth. What size cake is it? How much do similar cakes sell for in you area? You may need to call around to get some prices. Other things, cake board, cake boxes.
Thanks cakes22 for ur reply.I can't attach my picture in the attachment,I don't know why,but it is in my photos,the pink cake with the tiara.I used box mix,,it is a two layer cake,first layer is 10 inches and the top one is 6 inches.I don't know how much will I consider for my time and effort.I am new to this ,I don't have any idea.thank u for ur help,really appreciate it!