How to Get started with Amphetamine
Once you’ve downloaded the app, click Continue on its opening page, then Next on the following pages to learn more about each of the app’s features. At the end, click Finish; the app’s icon is then added to the menu bar’s right end.
Ctrl-click on Amphetamine’s menu bar icon to activate the app. By default, this will keep the screen alive indefinitely. Click the icon to see additional options, including the ability to change the duration for which your Mac stays awake.
Go to Amphetamine > Preferences and turn on “Launch Amphetamine at login” to ensure the utility is always available. Also check “Start a new session at launch,” and use the Default Session Duration pop-up to set session length.