First, we highly recommand that you get a shift boot adapter/retainer to help your new shift boot hold in place below the shift knob. This part can be easily found on the internet, such as Amazon or Ebay.
Make sure you choose the proper shifter thread according to your vehicle!
Also make sure your knob isn't attached to any other lever/mecanism, or you will have to buy a special adapter for your car.
From personnal experiences, we recommand that you fix the base of the shift boot with double-sided tape to avoid damage on the fabric and on your shifter console.
We highly recommand that you watch installation tutorials on Youtube to properly install your new shift boot. Just write "how to install shift boot" and there you go ;)