When i bought some castings (directly from the worm farm) i was given an instruction sheet on making tea,i dont know if its right or if there really is a true right way but i will post what i was told.

Steep 1 litre of worm castings and 1 teaspoon of molases in 10 litres declorinated water ( you can use an aquarium air pump with airstones or stir often) for 24-48 hrs. Drain off liquid, dilute 1 part tea to 4 parts water (declorinated) and water your plants or apply as a foliar spray. (for best results use within 4-6 hrs.) Solids may be added to your garden / flower beds or as an accelerator for your compost pile.