Help. Bamboo plant? Thanks?

I recently bought a bamboo plant with pebbles at my local flea market. Its been about three days. It still has a little bit of water so id rather water it when the pebbles are dry. I put it under my lamp for a while. Sometimes under the sun but ONLY for a little bit. I want it to grow fast so if I buy green green , do I put the soil on top of the pebbles? Or take out the pebbles and put the soil? Also, will the bamboo grow longer too? Or only the leaves ? Thank you for ur time (: