Della, as to how you could mount light fixtures in your horizontal refridge would be quite easy. Most all light fixtures like this come with hooks and chains for adjusting height so all you'd need to do is screw anchors in on each side (or top and bottom) and suspend it from there. You can adjust your height by raising or lowering the hooks on your chain. In the case of the grow light I showed yesterday you would simply remove and use only the light fixture. But there are other cheaper options set up wise, too, although they aren't quite as efficient. Here's another set up I use utilizing double T8's, 3000 lumins each, 32 watts each or a total of 6000 lumins at 64 watts:
: shop like fixture (less than $20.00 US)
: note double dome reflector
: Sylvania Gro Lux bulbs (about $8.00 each, US
: slots for hooks (usually included)
Other items you'll need would be a timer and thermometer, of course. If this were not a metal enclosure, an RF remote thermometer would have been great.
But, like I say, usually I put my seedlings in the greenhouse in the fall when we get a few light frosts. They get an extra 2 or 3 or maybe sometimes 4 weeks growing in there and then they eventually go dormant or freeze off in there. The only other time I got into a circumstance of very late growing was last fall with some late germinaters that I grew throughout the winter inside, have now been forced dormant and are currently in cold storage (I'll update in another thread)
: shop like fixture (less than $20.00 US)
: note double dome reflector
: Sylvania Gro Lux bulbs (about $8.00 each, US 
: slots for hooks (usually included)
