How much do you want for the used shifter? And why do you have an extra one if your putting one on? Anyways.. take that black ring off you were talking about
There's four screws, i think 8mm that hold's that rubber boot down. Take that off and theres the shifter bolts. Just 4 bolts.. Think they are 10mm from factory. Take it off, put some silicone on the new one and reinstall