I have a Worm Factory (maybe the same as you; not sure). It was made originally in Australia, even though I acquired it in the States. it has three feeding trays, one collector tray, and what I refer to as a "leachate" tray, which has a spigot/tap to drain excess leachate out of the apparatus.
When you first set up the worms, place ONE tray on top of the "leachate" tray (this may also be what you're referring to as the "collector" tray; it's the one with the spigot/tap). Use damp newspaper or coir or other suitable bedding (damp brown leaves?), give the worms some food, and let them get started. Feed them periodically, e.g., once a week or whenever the previous food is starting to disappear.
It will take them a while, but eventually, they'll pretty much fill that first tray with the slotted bottom and want to strike out for new pastures. THIS is when the second feeder tray comes into play. Add damp newspaper or coir or other suitable bedding (sound familiar?
), add food, and wait for the worms to migrate "upstairs." However, the lower tray must be very full; worms can't just jump from the lower level to the next one up!
Later on, this scenario will be repeated, and the third feeder tray can be added to the top of the system, with new bedding.
As the worms eat their food and use up their bedding in each tray, additional bedding is needed. I add food much more often than I need to add bedding, just as an example; I don't know what the balance is for other people. I also check to see whether there's excess liquid in the bottom tray. If there is, I pour it out through the spigot and dilute it 9:1 with water (a 10% solution of leachate) and water my plants with it for nutrition. This is sometimes referred to as "worm tea," but to use consistent terminology, I simply call it "worm leachate."
Why? Some gardeners use worm castings to make their "worm tea," and I think it's too confusing to explain, so I just call mine what it is: worm leachate. The leachate needs to be drained off, anyway, because too much moisture in their environment will attract organisms that bother the worms, fungus gnats among them. Good animal husbandry (if I may...) urges us to provide the best environment we can for our hard-working invertebrates, and a well-ventilated, moderate-temperature, non-acidic, well-drained home sounds like that to me.
It will take some time for the castings to build up sufficiently for harvesting. Please search this forum for posts by me from 2009 (I think), which is when I first harvested castings from my Worm Factory, established in 2008.
Have fun and happy gardening!
Sunset Zone 17, USDA Zone 9