Start > Run > CMD > IPCONFIG /ALL
If I were you I would get a switch / router / firewall to share the connection. Not that expensive, and a much better solution overall. You can have wifi as well, and have the ability to add further PCs / printers also. Much more secure with built-in hardware firewall, and much more robust. Plus, you only have to leave the router on, not the other PC when you want to access the internet from the lappie.
And it is probably easier to set up and maintain.
Instructions to set up ICS (internet connection sharing) are best obtained from the MS website. Lots of good stuff there on home networking.
Also some stuff in the FAQs on this forum.
SD