Restoring frogs being virtually illegal? Maybe there is a good reason for this? Why did the frogs disappear in the first place? If you know what that is, and have addressed it, frogs should move back into the area. Restoring frogs can do more harm than good. The movement of frogs and tadpoles about the place by well meaning "conservationists" can spread chytrid, further decimating frog numbers. Also there are several "feral" populations of native species in areas they are not meant to occur. Poorly identified tadpoles can result in cane toads being moved to new areas.
Building a pond with certain characteristics can encourage some pecies of frog. Low vegetation over the side of the pond often results in heaps of striped marsh frogs. Building a pond with 25cm high walls will stop ground frogs..... leaving it free for tree frogs to breed (most Litoria).
-H