Creating 301 redirects
From Joomla! Documentation
We often need to create redirects to point an old page at 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 page, after the end of the core Joomla! SEF section, simply append any redirects.
If you're not confident using redirects, check out
This site allows you to create a number of different redirects - if you're redirecting single pages simply enter the old URL and new URL in the fields highlighted below, and when you generate the htaccess it will show the code in the box on the right hand side. Copy this, and paste it at the very bottom of your htaccess file.