Place a layer of substrate across the bottom of the tank. If you plan to use plain gravel, wash it first. Keep rinsing it until the water runs clear. For other types of substrates, follow the manufacturer’s directions. Note that some should not be rinsed. Gravel will not contain any nutrients for the plants. Speak to an aquarium supply store representative to determine the nutrient supplements you’ll need for your specific plants.
Move the substrate around to form inclines and gentle slopes. Guitarfish.org notes that sloping the substrate so the back is higher than the front adds visual depth to the finished aquascape.
Place rocks and driftwood around the tank. The size and smoothness of the rock needed varies based on your plans for the aquascape. Don’t overload the tank. You will add plants and fish later, and you don’t want them obscured by a mound of rock.
Tie plants to whichever rock is the main focus of the tank. Work on the rest of the tank layout according to height, from low to high. While some plants such as hairgrass come in pots -- Aquarium Info notes you can plant these straight into the substrate material -- others such as moss and ferns must be tied on with thread or fishing wire. Tie these around smaller rocks to create green hills. Wet Web Media suggests letting algae grow on the rocks for additional green cover. Wind moss around branches and between rocks to form grassy ravines.
Add layers of similar plants of different heights to the substrate in front of the rocks to give the illusion that the ground is rising.