Sharing Preferences on Your MacBook
The Sharing preference settings on your MacBook enable you to control all types of sharing and to change the default network name assigned to your MacBook.
Click the Edit button to change the default network name assigned to your MacBook during the installation process. Your current network name is listed in the Computer Name text field.
Each entry in the services list controls a specific type of sharing, including DVD or CD Sharing, File Sharing (with other Macs and PCs running Windows), Web Sharing, Screen Sharing, Remote Login, Remote Management (using Apple Remote Desktop), Remote Apple Events, Xgrid Sharing, Internet Sharing, Bluetooth Sharing, Scanner Sharing, and Printer Sharing.
To turn on any of these services, select the On check box for that service. To turn off a service, click the corresponding On check box to deselect it.
From a security standpoint, you should enable only those services that you actually use. Each service you enable automatically opens your Lion firewall for that service.
When you click one of the services in the list, the right side of the Sharing pane changes to display the settings you can specify for that particular service. Note that some services may be disabled, depending on the hardware connected to or installed in your MacBook.