How to grow mushrooms in a growing kit?

I bought a mushroom growing kit last weekend and after setting it up I stupidly threw away the box it came which happened to have the growing instructions on it. This is how far I have got. I put the soil over the top of the compost stuff in the tub provided. I have been spraying it with water daily to keep it moist and have had it covered over in a dark warm cupboard for 8 days now. White furry stuff has now started to form over the top of the soil. Where do I go from here?