Are you certain that the Apple Pencil that you have purchased is compatible with your iPad model? There are four different Apple Pencils - each being compatible with specific models of iPad. They are otherwise not interchangeable.
Here is Apple's definitive compatibility list for the available models of Apple Pencil and iPad:
Apple Pencil compatibility - Apple Support
This video outlines pairing of Apple Pencil with compatible models of iPad:
How to connect and pair your Apple Pencil with your iPad - Apple Support
iPad User Guide also provides specific guidance for pairing and charging of the four different Apple Pencils:
Pair and charge Apple Pencil (1st generation) with iPad - Apple Support
Pair and charge Apple Pencil (2nd generation) with iPad - Apple Support
Pair and charge Apple Pencil (USB-C) with iPad - Apple Support
Pair and charge Apple Pencil Pro with iPad - Apple Support
If you experience difficulty pairing compatible models of iPad and Apple Pencil, this support page provides appropriate guidance:
If you can't pair Apple Pencil with your iPad - Apple Support