Pretty hard to do without a PC. Normally you would set it up via software since there really is no interface on the printer. The only way to hook it up to your WiFi LAN is via WPS, so that needs to be enabled/working on your router first. If it is:
Touch the WPS button on the router, it typically will flash a light to show it is working, then hold the WPS button on the 3260 until it blinks. Then wait. If the WiFi Status light turns on and stays lit, it is connected.
Now, hold the Cancel button on the printer for just under 4 seconds to print the configuration report, when that prints it will list the IPv4 address on it. You can use the IP address to access the webpage built into the copier to configure anything else you want to configure.
AFAIK, the 3260 doesn't support MOPRIA, so no direct print from Android, it just does Airprint which is Apple only. It does have Google Cloud print, but Google is killing that service.
WiFi Direct may be able to get you printing, but AT&T routers won't let it work unless you don't connect the printer to their router