Where can i seal my cake

Agree with Cynthia. In our area (Seattle) the local public health also covers Farmers Markets, so you can't sell there if you don't have their approval. The same rules would apply if you were selling to individual customers (retail) a whole different set of rules (through the State) would apply if selling wholesale. You might go to a local Farmers Market or other location where you would like to sell, and ask similar vendors what rules apply to them. Also, don't know about your location, but here each of the relevant governmentals have good websites explaining the relevant rules.

Thank you for your comment
I live in columbus ohio and i don't know how can i start my own work

Your cake looks lovely. I live in Calgary, Alberta. Where are you? If you are near Calgary there are several markets where you might be able to sell your cakes or you could get a write-up in a local paper that would get business going.