How do I connect my Iphone to my WIFI Epson printer?

Many Epson printers (including mine - an Epson WorkForce 645) have AirPrint technology. If yours does, here are the simple steps to use it with your iPhone.

Use AirPrint to print from your iPhone, iPad, or iPod touch - Apple Support

Also note Epson has an app in the App Store called Epson iPrint that allows you to do some maintenance and other functions (e.g., scanning) using your iOS device.

The printer and phone need to be on the same WiFi network. See here for help https://support.apple.com/en-us/HT201311

Enjoy your new iPhone!