In a ground installation a frame is built for your solar cells that tilts them up to an optimal angle and faces the correct way (North in Australia & South in Asia). The frame can be built out of galvanized steel or aluminum, and is attached to the ground via a concrete foundation. In many cases the frame will be a rigid half a frame like structure.
Where achieving the maximum possible efficiency is an aim (such as in commercial or very large installations) it is possible to have half A-frames that are manually tilt adjustable, so that in winter when the sun is lower in the sky the cells can be tilted up for greater exposure.
Sun tracking installations are also available (where the cells rotate slightly throughout the day to follow the sun) and these are generally mounted on a vertical pole or beam (like a lamppost) to allow rotation.
Why would you ground mount your solar PV system?