If on Chrome/Chromium/Brave Desktop: You should see an install button on the top bar. Its minimized form is a circle with a plus sign in the middle. If you do not see it, check if you are running the latest version of these browsers.
If on Safari: Click the share button. Find the 'add to home screen' button If you do not see it, check if you are running the latest version of safari or os x.
Special note for Linux: We have released a desktop app on the snap store. Press the button below for details.