Start with the fuse, but won't be surprised if the brake switch up on the brake pedal isn't the real problem.
See "Related Questions" below for more
See sources and related links below to lookup Ford Windstar brake light lamp part numbers by vehicle year.
brake light bulb out
If the red " BRAKE " light in your dash is on that indicates that either your parking brake / emergency brake is on , or the BRAKE FLUID LEVEL in your brake master cylinder ( located in the engine compartment ) IS LOW
In a 2000 Ford Windstar : ( DOT 3 brake fluid meeting Ford specification ESA-M6C25-A ) according to the Owner Guide
On a Ford Windstar : I ASSUME since the first model year ( 1995 ) I was looking at the 1996 Ford Winstar Owner Guide and it definately has the high mount stop lamp
You are supposed to only have to press the brake pedal. Evidentally your brake lights aren't working. You probably need to see if the brake light switch is bad.
DOT ( 3 ) brake fluid
The brake fluid level may be low in the reservoir. If the reservoir is low it's telling you the brake pads are worn down. As the brake linings wear down the fluid level drops and eventually turns on the brake light. Have a mechanic check your brakes soon. See "Related Questions" below in case the brake light in question is/are the ones in the taillights. Not uncommon for Windstar brake lights to turn themselves on.
That's your LOW tire pressure warning light in a 2002 Ford Windstar
The parking brake is only ONE of the triggers for the dashboard brake warning light.Before referring you to the "Related Questions" below, I'd suggest checking the brake fluid levels.
above brake pedel behind fuse block
have you check the tail light fuse to see if it is blown. other possiblly is the headlight switch.