Reboot. When the system first boots watch for a message that says something like: To enter setup (or bios) press....
For emachines it should be either the DELETE key or the F2 key I believe, but what ever key it says, that's the key to press. Once in bios be careful not to change ANYTHING except for the Wake on Lan setting, and then only if it is on (you want it off). After you make the change, click on SAVE CHANGES AND EXIT