You should be able to draw a regular wall and "paint" it with a stone texture. You need to draw the wall using Wall option under Building menu. In the same Building menu > click Paint > from the left panel > click Wall Style > select a stone texture > click OK > click the wall you want to paint. Note that in the Textures window, you can import textures from third party sites.
To draw steps on the ground, I would recommend you to use the Path tool. Under Exterior menu > click Path > draw a small square or rectangle > using the red and purple balls you will see after drawing it, you can change the size and shape of the steps. You can draw as many steps as you need using the Path tool. You can change its texture the same way I explained for walls.
NCH Software formally takes suggestions or feedback about products through the form at http://www.nch.com.au/suggestions/