.i am new to the modem world....i need info on the best network's modem 2 buy....mtn or etisalat...i mean in terms of being cheap and fast

Get the cheapest 3G modem and unlock it. This will give you the opportunity to use MTN, Etisalat, Glo or Airtel line with the modem. You can then compare the prices of data plans of different ISPs and subscribe to the network that pays you. Before subscription to any, it is very important to be sure that the chosen network is very good in your location.

For me here in Ota, Ogun state Visafone is friendly. You may try it in your area.
This is just an advise.
Idotun