Você precisa ativar o compartilhamento de conexão com a Internet.
Go to Control Panel, select Network and Sharing Center.
Click on the link "Set up a Connection or Network".
Select the option “Set up a wireless ad hoc (computer-to-computer) network”.
Type in the Network name and select the Security Type (WPA 2).
Click on "Turn on Internet connection sharing".
Ajuda e instruções do Windows: Configurar um computador -ou-computador (ad-hoc)