[otrs] otrs-fetching mails from mail server

HI I'm new to otrs.i have installed otrs and configured.everything is working fine.i can able to fetch the mails from mail server via postmastermail account. now i want to fetch the mail for every minute. i read the otrs doccument.but i can't understand..can any1 tell me how to do..pls tell me which file to edit and which service should i start so i can fetch my mails for every minute. -- Regards, B.Karthick.