Creating 301 redirects
From Joomla! Documentation
We often need to create redirects to point an old page to a new page.
While this is possible to do with extensions, it's very simple to add to your .htaccess file. At the bottom of the file, after the end of the core Joomla! SEF section, simply append any redirects.
If you're not confident using redirects, use the .htaccess Generator.
This site allows you to create a number of different redirects. If you're redirecting single pages, enter the old URL and new URL in the fields highlighted below. When you generate the .htaccess file, it will show the code in the box on the right hand side. Copy and paste it at the bottom of your .htaccess file.