How to connect internet in promate usb modem?

i am having a promate usb modem in which we could put sim card in it and net in high speed. i had put my airtel sim in it. but it saying failed to connect internet. i had put net booster also. in the advanced setting option its showin username password domain phone number apn lik that. what to i have to type in those. pls tel me a way to connect to internet through that.