Fill the pot nearly to the top with cactus mix potting soil (sold at any nursery or garden center).
Slightly off-center, strew an odd number (three or five) fist-size rocks to suggest natural terrain.
Add a high plant, also off-center, such as a dwarf Euphorbia milii cultivar.
Tuck in small rooted succulents and cuttings so they appear to have grown among the rocks. Vary the plant colors and textures, and arrange so no soil shows.
Add contrasting hues of black lava rock and white pumice to cover remaining bare soil, then add crushed, tumbled glass atop the pumice for sparkle in the topmost layer.
Give the composition half a day of sun in all but desert areas, or keep it in dappled shade. Water it thoroughly twice a month and protect it from excessive rainfall lest the plants rot. Overwinter it indoors if temperatures in your area drop below freezing. Gradually introduce it to greater sunlight in spring to avoid sunburn.