Common issue - lots of posts on this problem on this forum, you may want to do a search.
Check to see if the brake lights are functional when you step on the brake pedal. If not, replace the brake light switch.
If the lights are working - you will have to remove the shifter knob and bezel (and I think the floor console too). There was a TSB regarding wiring that became damaged, and prevented the brake-interlock shift solenoid from operating, and allowing the driver to shift out of park. The solenoid assembly was mounted to the transmission floor shifter assembly.
The wiring TSB stated to re route the wiring, and repair any that pulled out of the connectors. I believe the wiring pulled out of the connectors when the shift lever was pulled further rearward than placing the lever in drive.