I decided to build a "frame" of concrete to hold the stones inside the area, so I started with that. I used many different wooden planks and pured concrete inside of them. I measured carefully the dimensions of the yard I would like to have, and then put the wooden planks. In order to make them steady for the concrete, I nailed them on wooden spikes I put on the ground. For the planks to be on the right height i used a level and my measure tape and I had to dig some dirt to put the planks in the right place.
I made the concrete with the help of my father. It was just regular conrete mixed with sand and some gravel to make it stronger. We mixed it in the wheelbarrow, because we didn't have a concrete mixer. After that we poured it in betweeen the planks and straightened it. We let it for a day to dry, pouring water every few hours on the surface so that it wouldn't crack.
DIMENSIONS: The frame was 20cm in width and had around 8 cm of height. The overall area was about 10 sqr meters ( not much, but I used plain conrete and gravel for the rest of the yard)
ATTENTION: You want to know in advance where do you want the rain water to head. Every time you pourconrete you have to be aware of the slopes. You do not want to have puddles of rainwater in the middle of the sitting area, so be extra careful with the level. It is, however, almost certain, that no matter what you'll do, there is going to be some puddles of water. The tiles do not have a completely even surface
The stone tiles are used mostly to what I know to be called "crazy paving". Although, I used here a diferrent technique. The gaps between the tilew are far larger, and the tiles themselves are different. They come in a variety of colors, mostly black, drey-green and blue.