Get some string from a spider and click the ground. In chat a region info will pop up to say if the area has a region or not. If you walk far from spawn you will find more open spaces and can build away from other players areas. Once you have a nice area make a petition ingame to have it region protected, just make sure you are not close to anyone else's regions else they will deny your petition.
You could always do what I did when I first started on Minetown... Go to the Warp Lounge (/warp warplounge) and right click on a city's sign and just walk for a bit. You'll eventually find some free wilderness to mine and build. Make sure you stay a good distance from other people's buildings... There is plenty of map to choose from!
I have nto disseapped if yo uare referring to the stall tha twas made of gold and diamond blocks, I have moved to A shop lot on the uppermarket now, I still sell idamonds and gold. /warp DGspot is the new shop warp