After old shift knob is off how do you put a new one on?

To install a new shift knob, first ensure that the threaded post on the shifter is clean and free of debris. Align the new shift knob with the post and screw it down clockwise until it feels secure, but avoid overtightening to prevent damage. If your new knob has a set screw, tighten it using the appropriate tool to ensure a snug fit. Finally, check that the knob is positioned correctly and operates smoothly.