help with network lan setup

i know this quesiton has probably been asked a lot but i cant find a solution other than things i have already done.

issue is: I have a windows 7 laptop on wireless and a Imac pro lion lastest updated, I have enabled smb sharing for lion. I have an external hard drive connected to the mac via USB. I have shared it out. on the imac i can see the hp laptop but can not login to any shares on it with the local user id and password on the laptop nor can i browse to the mac on the windows laptop and access the shared external hard drive. I can ping both machines from windows and vice versa so no issue their they are alive. i just cant get the hard drive shared out properly for the windows laptop to see it and access it. is there a tutortial out there for step step any help would be appreicated thanks.

why cant anyone help. this has to be an easy fix. my main goal is to access my Imac via wireless lan. both machines are on wireless. i can ping the imac, see it on the network under network places but cant access the external hard drive that is connected to the Imac via usb, i have shared it out via smb etc it prompts for user name and password i put that in does not work. I dont know what the helll.

When authenticating to a computer you should use this method:

machinename\username
password

i.e. if the computers name is mac and the user's name is Joe and you are asked for the userass when connecting,...

mac\joe
password

Same on iMac

If the PC name is Win7 and the user is Bill, on the Mac you want to access something on the PC, when asked for userass

Win7\bill
password