There are tons of information on RC how to do it. Search for in detail instructions.
In short you have to cure them to remove any dead organics off the surface.
More organic on the rocks - longer time it will take to process all of it. So initial stage to clean the rocks off any left over organics is essential to cut your curing time. Scrubbing (with tools), bleaching (with bleach), dissolving (with acids) all of these could be applied on this stage. Then you just put your rocks in the Brut and start curing (search for details). GL!~