If you want to share files with a Windows 7 pc from a mac there are a few steps to take.
First on the Mac open System Preferences then open the Network tab.
Then open the Advanced tab , then look for and open the WINS tab
You will then need to enter your Windows ” workgroup ” name in the workgroup tab.
You can find your workgroup name from your windows system in your windows system’s Control Panel
When you have done this press OK
Now still on your Mac and in system preferences open the Sharing tab
Put a tick in File Sharing and click on File Sharing , this will change the right hand side of the screen where you can select the folders you wish to share.
Next you can change the permissions (rights) given to the shared folders eg:read only , read & write etc
Next go to options and place a check mark in the Share files and folders using SMB , then click Done.
The last thing to do is open your Accounts tab in system preferences , unlock your system & then click on Guest Account . Put a check mark in the box that says Allow guests to connect to shared folders