what do you need to do to be able to sell your art in Jackson square

St. Louis Cathedral had no input on performers or venders. If you want to sell art, you need to submit a portfolio and obtain a permit from City Hall.

I would assume you need a permit to sell.

Get Permission from The Local Government

You need to talk to the local officials

Speak with the ppl at St. Louis Cathedral. They give permission to the street vendors and performers.