If you live in the US, you will need to check with your state and county to find out all the requirements for cottage food operators. Then get properly licensed.
If you intend to produce from you home kitchen, you need to find out if the farmer’s markets you intend to sell from allow sale of food produced from a home kitchen.
California, the state I live in, requires food sold at a farmer’s market to be produced in a commercial kitchen. If you live in such a state, you will need to find a commercial kitchen to rent. Talk to the staff and advisors at your culinary school about where kitchen rentals in your area. Also google hourly commercial kitchen rental to begin search in your area.
Aside from the required business license and permits from the state and county, you will need to apply to the farmer’s market association. If they accept your application, they you will have to obtain a health permit, insurance, and whatever else they require to operate at the market.