In the 2nd bin (middle) add some layers of bedding and food for the worms.
Tear up newspaper or any type of paper product that you would normally recycle. These paper products will make the bedding for the worms and should be around 2" deep and not compacted down. Make sure the bedding is fluffed up and has plenty of air pockets for the worms to move around.
For the second layer on top of the bedding add organic material such as grass clippings, food scraps, or leaf/yard waste.
Keep the lid on the 2nd bin and don't place the 3rd bin(top) until half of the bin is filled with compost and the worms are ready to migrate up to the top bin. Repeat bedding and food layers.
For the final touch add your wiggly friends on top of the bedding and food in the 2nd bin (middle.)