Once you have installed CCleaner you can open the application by either:
1. Double-clicking the CCleaner desktop
2. Clicking on Start Menu -> Programs -> CCleaner
3. Right-clicking on the Recycle Bin and selecting "Open CCleaner..."
Note: There is also a "Run CCleaner" option on the Recycle Bin menu, which will clean your system without any prompts. But we recommend you don't do this until you have familiarized yourself with the program and its options.