The LisaGuide diskette doesn't actually have LOS on it in any form. That is, it doesn't have SYSTEM.OS, SYSTEM.LLD, or any of the other system files needed to boot the OS; it only has the LisaGuide executable and related files because there isn't room on a 400K floppy for anything else. Heck, there's barely room for the executable; that's why it has to be packed!
What you have to do is boot your existing LOS installation on your hard drive to the Environments Window with the LisaGuide diskette inserted, and then there should be a LisaGuide option that pops up as a second environment next to LOS (or a third if you've got the Workshop installed too). Just select and boot into that, and you'll be up and running.
Not sure if you've ever booted into the Environments Window before, but the easiest way to do that is to shut down LOS (hit the power button) while holding the Apple key. It'll say that it's returning to the Environments Window instead of turning off. Once you're at the window, choose the No Default option, which will cause it to go to the Environments Window on every boot instead of autobooting into LOS. This way, you can pick between LisaGuide and LOS every time. Just make sure you have the LisaGuide disk inserted as the Lisa is booting to the Environments Window or else the LisaGuide entry won't show up!
For more info on what the Environments Window is, go read my write-up in the Lisa source compilation readme 
here. I describe the whole boot process, including the role of the Environments Window (SYSTEM.SHELL).
And dang, I had no idea that the Selector could show a splash screen! How cool is that?