I just replaced my transmition wire harness, and when trying to replace this switch you should inspect all the wires to make sure they are not crack and deteriorated. You must first turn the white plastic ring approximately ¼ of a turn toward the bottom, and once you have turned the ring you will notice that the black plug gets loose. Also while you changing the switch you may also want to change the gear shift plastic bushings (two of them required).
I paid for the new wire harness $ 139.00 + plastic bushing 0.70 cents each.

As per the shifter knob, you have to remove the small plastic cover on the top of the shifter and remove the bolt. Once you remove the bolt you have to twist the knob while holding the black piece at the bottom of the knob. By the looks of the picture that you attached, you may need to do this in order to install the black dust strip shown in the picture loose and hanging. This is fairly easy to do.

Regards,

Norman