Let's assume you've replaced your old site with a brand new one. We'll try out how the Redirect Manager component works by entering a nonexisting, old URL and telling the Redirect Manager what new page it should show instead. This can be done as follows:
Navigate to Extensions | Plugins and search for the Redirect plugin. Click on its status icon to toggle the status to Enabled.
Go to Components | Redirect to open the Redirect Manager: Links screen, as shown in the following screenshot:
Through the course of time, this screen will automatically be populated with broken links (expired URLs). These are URLs that visitors have entered or clicked on in their browser and that have generated an error page. Clicking on an expired URL will allow you to enter a redirect URL. However, if you've just installed Joomla or if your site isn't live yet, the Redirect Manager: Links screen won't contain any expired URLs.
Click on New to open the Redirect Manager: Link...