Just to restate what's above, because you probably have a WDW point of view.
IASW is at the very back of the park kind of set away from Fantasyland. The parade starts there, goes behind the main FL attractions, between the castle and Matterhorn. Then through the hub and down Main Street.
As noted if there are two parades in a day the second one goes in reverse.
For those with the DL point of view in WDW MK it goes, from where the NOS train station is in DL, next to Splash in MK(HM is in a different place in the MK). Goes along the bottom or ROA. Into the Hub and down main street. Exits next to the Fire Station.