anyone know where to ground black wire to chasis

[nachumama]

since installing my new radio, i cant get any radio stations. called crutchfield about it and they told me that i have to ground the black wire to the chasis of the 2006 nissan pathfinder... not just any metal. can some one tell me where can i ground this wire so i can get good fm reception again? Please help me. they also told me to connect solid blue to blue+white wire as the antenna connection.

[smj999smj]

Most usually just run the wire to one of the radio mounting screws. Any grounded metal part of the car can service as a ground for the radio.