Step 1 − Launch Firefox and navigate to the following URL - http://seleniumhq.org/download/.
Under the Selenium IDE section, click on the link that shows the current version number as shown below.
Step 2 − Firefox add-ons notifier pops up with allow and disallow options. User has to allow the installation.
Step 3 − The add-ons installer warns the user about untrusted add-ons. Click 'Install Now'.
Step 4 − The Selenium IDE can now be accessed by navigating to Tools >>Selenium IDE.
Step 5 − The Selenium IDE can also be accessed directly from the quick access menu bar as shown below.