My team is rebuilding and we want to add encoder wheels but I have no idea how to code them
You should just be able to use the encoder functions. See the api for more info:
https://api.vexcode.cloud/v5/html/classvex_1_1encoder.html
The api will have all of the functions that you can use with the encoder. Just choose which one you want to use.
How so, do mean integrating them in your design, or in your code?
Integrating encoder wheels depends on what you want to do with them. Do you want to track the exact position on the field?, if so I would refer to a post by team 5225a to start. This is a major undertaking, but allows for amazing autonomous program flexibility.
A much simpler solution is to use the encoders for simple distance tracking. in this case, set the motors to drive forward until the tracking wheel detects a certain amount of movement.