To make garden steps for a long gradual slope, the landing to each rise will have to be extended a distance to match each rise. If you plan to use an eight inch rise and your hillside rises eight inches in twenty feet, your landings will need to be twenty feet long. If the rise on the slope is irregular, then your landings may be of different lengths to match.
The method of how to build garden steps like these is very simple. The actual steps or risers which are simply dry stacked without mortar work as a retainer to hold each landing in place. The landings going up the hillside slope are also laid in dry without the use of mortar or cement. Usually, a simple base of gravel is first laid down as a leveler and then more gravel or soil is added in between the rocks in the steps after they're placed.