Launch Ableton. Click the "Options" menu, then "Preferences."
Click the "File Folder" tab. Click the button next to "Use VST Plug-in Custom Folder" to toggle it to "On."
Click the "Browse" button next to "VST Plug-in Custom Folder." Navigate to the folder that contains your VST plug-ins; this is nearly always either "C:\Program Files\VSTPlugins" or "C:\Program Files\Steinberg\VSTPlugins." Click "OK."
Click the "Rescan" button next to "Rescan Plug-ins." Ableton scans the specified directory for VST plug-ins and activates them in the browser.
Open the project in which you want to work in Ableton. Click the "Plug-in Device Browser" icon, which looks like an electrical plug, on the left side of the Ableton window. Scroll through the list of VST plug-ins until you find the one you want to use.
Click and drag the VST plug-in onto a track in the mixer window. You can add a VST effects plug-in to either an audio or a MIDI track; VST instruments, however, only work on MIDI tracks.
Click the title bar at the top of the track to view the VST plug-in's interface. If the interface doesn't appear, press "Shift" and "Tab" simultaneously to reveal the plug-in device section for the track, then click the wrench icon on the VST plug-in to bring up its interface.
Click and drag the VST plug-in's controls to adjust its parameters. If you've added a VST instrument to the Ableton set, you can now play it using a MIDI clip or an attached MIDI keyboard. Repeat the process for any other VST plug-ins you want to use.