Huh, wild. Usually it's not a slot, but a covered drive on the side accessed by either a small button or a key on the keyboard.
For stuff that truly has no optical drive, Windows is usually pre-loaded with a recovery disk in a partition, or has to be accessed by USB flash drive that has a Bootable copy of Windows or a Windows install.
If you have access to a regular pc, you can make a Bootable windows drive easily enough.
I'm just surprised you bought a new laptop that included a Windows disk that had no optical drive.