Welcome!
To see what you need to do, go to https://duet3d.com/wiki/Duet_Wiki and look at section "Getting started with the Duet WiFi". There is also a Quick Start Guide on that page.
The main steps are:
1. Make any necessary changes to your wiring harness to suit the Duet. In particular, the endstop connections and the Z probe connections will almost certainly be different. See the Hardware and Wiring section of that wiki page.
2. Get connected via WiFi. See the Getting connected to the Duet WiFi link.
3. Generate config.g and homing files for your printer. See the links in section Firmware configuration (Duet Ethernet & Duet WiFi).
HTH David
