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 non-existing old URL and tell the Redirect Manager what new page it should show instead:
Go to Components | Redirect to open the Redirect Manager: Links screen:
In the course of time, the Expired URL column in the Redirect Manager: Links screen will automatically be populated with broken links. These are URLs that visitors have entered or clicked on in their browser and that have generated an error page. Clicking 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 screen.
In the Source URL field, enter the outdated URL. Make sure to enter not just any wrong URL; it should contain the domain name from the current site. Replace
www...