The British Biochar Foundation website FAQs provides a great overview of Biochar - particularily if you are new to Biochar or looking at how to incorporate it into soil.
"A simple treatment would be:
1.Add biochar to a water filled container, 2.Add some plant food, 3.Add some compost, 4.Allow it to stand for a week or two stirring occasionally 5.Strain liquid and use as a feed/compost tea and add biochar/compost blend to your soil or compost.
Untreated and treated biochar is best mixed into the soil by adding it to compost, manure, slurry or some other organic matter and then adding this to your soil as you normally would". More can be read at http://www.britishbiocharfoundation.org/?page_id=52