I have no link for this, however I have known others who have done this. It is VERY EASY.
Basically, you buy interlinking larger pavers to form your desired shape. You buy gravel or stone. You buy small interlinking pavers.
The rest is pretty self explanatory. This was featured on Pinterest.
Great yard feature to put some chairs up, have some coffee, cocoa, tea, wine or make smores with family and friends.