first time using an mac and need to format (help please)

ok i have know idear if i am in the right place but i got given an iMac (exschool thing one if the first one to come out) now i have mac os8.5 and an copy of OS9 now os8.5 is not doing it for me and i want to up grade to os9 but it said i have to up date the firmware .

now dont laught as i have an little storru to tell , i had an good working copy of OS8.5 but it had ann the school stuff on it (mate perants are the techs ot the school so it was an writed off pc re biult not stolen) and i had an go at reinstalling OS8.5 but it sems i cant install any new software programs and i have know idear how to in the first place (it is an blind man leading the blined).and i thought i would have an go as puting OS9 on but it wont let me with out an firmware up date .

ps:i dont have the net as i am at an mates place