Here is a commercial glass lid:
http://www.aquariumguys.com/glasscanopy1.html
It consists of two panes of glass joined by a plastic hinge, plus a strip of plastic along the back edge which may be cut to accomodate cords, airlines, filters, etc.
You can make your own glass canopy with two appropriately sized pieces of glass, with a bead of slilicone run on top of (not inside) the joint to form a hinge. You can also use packing tape to make the hinge, but you will have to replace the tape every few months.
You can silicone a cabinet pull to the front pane of glass to make it easier to lift.
If you need to have cords or airlines coming out of the tank, cut a corner off the back piece of glass. If this leaves too large a gap when the cords are in place, you can stuff the gap with fabric or filter sponge to prevent the newt from crawling through it.
Hopefully this helps to make things clear:
Of course, you can also just lay a sheet of glass on top of your tank and not fool with hinges. The hinged top is nice because you can leave your aquarium light sitting on the back part of the glass while you lift the front part. If you don't have a light sitting on top of the tank, a single sheet of glass will work just as well.
