Question

How I can use WI-FI on a cellphone having only GPRS?

Answer 1

You cannot use WiFi if your phone is not fitted with a WiFi trans-receiver.

GPRS system is an integrated part of the GSM network switching subsystem in simple words GPRS connects directly to carrier (service provider).

WiFi works on entirely different frequency and rage of WiFi devices is limited to a few meters only.

Answer 2

I agree you won't be able to access it unless your phone is setup for it. Maybe consider buying a new phone. Hope this helps.