Now your worms have been working hard eating, pooping, and reproducing so now it is time to harvest the fruits of their labor (worm castings) There are a few methods to harvest worm castings so I will briefly describe a few:
Dump and Sort Much like it sounds you simply dump out your worms and castings onto a plastic sheet. Sort through and catch as many worms as you can and set them aside.
Divide and Harvest Move you compost and worms to one side of your worm bin and fill the other half with new bedding. For the next couple weeks only bury food on the side with the fresh bedding. During these two weeks a majority of the worms will move over to the other side where you can harvest the castings minus the worms.
Moving on Up Create a second bin which you place on top of your existing one (Rubbermaid containers and 5 gallon bucket worm bins work great for this) and fill it with clean bedding and food and after a couple weeks the worms will migrate into to the new bin. Now you simply harvest the lower bin.
Using any of these methods I would suggest using a soil sieve like I showed how to create previously to better separate food/bedding from the castings and either use the remains in your next bin or put them right into your compost bin.