Help - HTTP erroecode 404 and 302

[optional]

I found the following from my site's awstats :

HTTP Error codes
HTTP Error codes* Hits Percent Bandwidth
404 Document Not Found 781 78.9 % 3.28 MB
302 Moved temporarily (redirect) 206 20.8 % 2.98 KB

Can anyone pls care to explain what are these errors all about and how can i fix them, as they seem to be preventing a substantial percentage of my web site's traffic (which is not substantial at the first place :p)

[metasynman]

404 means the server can't find the specified file. If you have recently revamped your website or are in the habit of simply deleting outdated pages that have links to them, this will cause a problem. Your server logs can usually tell you which links are dead, and you should then create 301 redirects to active & relevant pages so SE's and users don't end up at a dead end.

302 isn't quite as large of a problem, but still isn't a good thing. 302 redirects should only be used for temporary redirects, generally used while you fix a section of your site or something. If a page or section has been removed and will no longer be available, you need to (again) create 301 redirects indicating a permanent URL change/move.