I clip the tape end off about 1/2 inch and leave the teeth. Make sure the brand of zipper tape and the zipper pulls match. It seems, they don't work across different brands.
Have you seen these tutorials?
https://www.sailrite.com/how-to-install-zipper-slider
https://www.youtube.com/watch?v=I_Wd6Bq4Vf0
https://www.youtube.com/watch?v=h7tG3xtV_Sk