How to configure a web server
 

How to configure a web server , with multiple root directories
and using Redirect

You probably want to check out how to work with apache's config files.

Look at /etc/apache2. There's a sites-enabled and sites-available in addition to apache2.conf. You place configurations for the sites in sites-available, and then use the a2ensite command to enable them (it makes a symlink in the sites-enabled dir).

this might help:
http://www.debian-administration.org/articles/412

First and foremost, I would recommend that you bookmark the following URL, Official Apache Web Server Site.

If you want to host multiple domains on a single IP, you would be interested in the VirtualHost directive.

Redirects can be accomplished with the Redirect Directive, or Mod_Rewrite.

ncoffield@hostmysite.com,
Server Engineer,
www.HostMySite.com

this would apply only if the Op uses Debian (maybe Ubuntu too, not sure how it looks there).

Other distros don't split up the files as Debian does.

http://jms1.net

search around his site, plenty of good info there.

Depending on the distro that use, there might be some GUI tool around that allows you to make all or most settings without accesing httpd.conf directly. Fedora has it usually (under Gnome) in the System/Administration/Services/HTTP menu.

By multiple root directories you assumably mean multiple webroot directories. Setting webroots is part of the generic settings of a virtual host. Howtoforge has a lot of tutorials aimed at webservices.

Debian

I think this is actually quite a nice feature of the Debian package -- albeit non-conventional.

i just bookmark
http://httpd.apache.org/docs/2.2/
http://dev.mysql.com/doc/
http://www.php.net/docs.php
http://www.phpmyadmin.net/home_page/docs.php
http://awstats.sourceforge.net/
http://www.perl.org/docs.html ( needed by awstats )