Submitting your new website to the major search engines is the first thing you should do once your website has gone live. After all there is no point having a website if no one I going to be able to find it.
You should only need to do this once and for a new website, after your site has aged and has acquired incoming links from other websites, the search engines should automatically find it and any updates.
No registration required.
http://www.google.co.uk/addurl/?continue=/addurl
Yahoo
Free registration required.
http://siteexplorer.search.yahoo.com/submit
Bing
No registration required.
http://www.bing.com/webmaster/SubmitSitePage.aspx
DMOZ
No registration is required but you will need to choose the best location in their directory for your site.
DMOZ is not a search engine itself, but it is used by a lot of other search engines and directories to help place your site. Google also uses it to get accurate site descriptions for their listings.