Wow, it's been a while since anyone's asked about Daylabs.

I'm sorry to hear the unit you picked up didn't come with the cord - the seller did you no favors!
A Daylab is also known as a slide printer. You take a regular slide (that you've shot using slide film), drop it into the slide holder, and look through the viewfinder of the Daylab to get it into focus on a plain screen. You load Polaroid or other instant pack film in the bottom of the unit. The "film type" button on the left of the unit will give the timer the correct amount of exposure based on the instant film's speed, so you set that in advance. The Lighter/Darker knob controls the aperture, like a camera, and generally starting at mid-range is a good place to begin. Notice the set of cyan/red/yellow levers at the top - that lets you control color cast, which can change dramatically from slide to slide. When the "ready" light comes on you make your exposure, pull out the instant film and let it develop.
Slide printers used to be widely used when Polaroid film was still around - for various alternative photographic processes like image transfers, emulsion lifts, or manipulations. This "Jr" model has limits on film types that the loader will take - probably was best for Polaroid 669, the familiar square format (I think that's the right number). Other slide printers have the ability to swap out bases....I don't know if this model does or doesn't.
I'd check online at
ebay or other auction houses to search for the power supply, or even a different model - they should be pretty cheap, if you really want to give it a try. If you like to shoot slide film, it's a fun way to get other results from your slide images. Polaroid is gone but Fuji makes lovely instant pack film, which is generally compatible with these systems, though I've not personally done it. I have a Daylab 35 Plus that takes up to 4x5 slide transparencies, and used to set it up and work on my kitchen table - no darkroom needed, and the processes are easy to learn and never fail to give unique results.
For excellent, step by step instructions, look for Kathleen Thormod Carr's old book on Polaroid processes. They're still around and very helpful, even though they will refer to Polaroid film only.
You might also want to call Freestyle Photo and inquire about a cord. Here's the link to
Daylab Corp, I think they sell through Freestyle now. Good luck - hope this helps!