To download Geometry Dash on your PC, start by visiting the official Steam website or the Steam app, as the game is available for purchase there. Search for "Geometry Dash" in the Steam store, add it to your cart, and complete the purchase. Once purchased, the game will be added to your Steam library. Click on the game in your library and select "Install" to begin downloading it to your PC. After the installation is complete, you can launch the game directly from Steam. Make sure your PC meets the minimum system requirements for a smooth gaming experience.