There are two ways to connect an Epson XP-900 printer to a computer via Wi-Fi: manually or using WPS (Push & PIN). The manual method involves selecting the Wi-Fi setup option on the printer, choosing the desired Wi-Fi network from the list, entering the password, installing the printer driver on the computer, and selecting the Wi-Fi connection during installation. Alternatively, Wi-Fi Direct allows direct connection between the printer and computer by displaying the printer's Wi-Fi Direct credentials for the computer to connect to without an intermediary network. The document then offers contact information for technical assistance connecting the printer via Wi-Fi.