I was there the other day and the guy next to us was there for this. He was given a form to fill in which told him what documents were needed - I think you can also find this info online on www.dubailand.gov.ae or www.rpdubai.ae.
The land department is in Deira, alongside the creek. Go over Maktoum bridge and take the underpass, second right exit off the bridge, and as you come up the other side of the underpass keep an eye out on the right. It's a few hundred yards along, with a big car park right in front of it.