Per City ordinance a permit is required before having outdoor entertainment. See ordianance below. You may also print out a permit application.

17.02 (5) (f)   For outdoor entertainment, which includes but is not limited to live 
music, disc jockeys, and karaoke machines, located in the C2 and PDD Districts, a 
written request outlining the date, time, location and type of entertainment must be 
submitted to the Chief of Police for prior approval.  If approved, the Police 
Department reserves the right regulate the loudness should circumstances warrant it. 
This section excludes events already approved under a Special Events Permit.
                  Outdoor Entertainment Request Form