☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. Select it in the results (it should be at the top.) ☞ Enter the first few letters of its name into a Spotlight search.
Launch the built-in Terminal application in any of the following ways: Sudo /Applications/OmniDiskSweeper.app/Contents/MacOS/OmniDiskSweeper Triple-click anywhere in the line of text below on this page to select it, then copy the selected text to the Clipboard by pressing the key combination command-C: Install the app you downloaded in the Applications folder as usual. The administrator account is the one that was created automatically when you first set up the computer. If you have more than one user account, make sure you're logged in as an administrator. To see everything, you have to run it as root. ODS can't see the whole filesystem when you run it just by double-clicking it only sees files that you have permission to read.
