How can I effectively set up a raised garden bed over a concrete slab?

To set up a raised garden bed over a concrete slab, first, ensure the slab is clean and level. Place a layer of landscape fabric over the slab to prevent weeds. Next, build a frame for the raised bed using treated lumber or composite materials. Fill the bed with a mix of topsoil and compost for good drainage and nutrients. Consider adding a layer of gravel at the bottom for additional drainage. Finally, plant your desired plants and water regularly.