Start the executable you just downloaded. If it crashes immediately, you may need to specify the path to your Songs directory from the command line like .\osu-bdi.exe --songs-dir "C:\Program Files (x86)\osu!\Songs".
Install the userscript from Greasy Fork or Github in your browser. A userscript manager such as Tampermonkey may be required.
Open the beatmap listing and you should see the effects after the page loads.
