Ubuntu by default (assuming you may be installing the desktop edition) does not have Apache, Mysql, and PHP running.

You will have to install them after words.
if you are completely new to linux you can install the packages by either using Synaptic ( System > Administration > "Synaptic Package Manager" ) or by installing it from the Terminal under Applications -> Accessories.

For this method were going to use the Terminal using a quick method.

Launch the Terminal and type:
sudo apt-get install php5-mysql

Normally I would tell you to install each package individually (apache2, php5, mysql-server etc) but this way Ubuntu will have to install them all to satisfy the dependencies of the package.

During the process it will ask you for a mysql root password, make sure to make note of it once set so you don't forget and finally once its all setup the services should be running.

Check your browser to see if http://localhost says It works!!

Next you can test out your site by editing files in /var/www/

I won't go into to much details as to get off topic from your main question. But some quick hints.

to stop and start the independent services you can use
sudo service apache2 start or
sudo service apache2 start
same goes for mysql or any other daemons running.

I recommending installing phpmyadmin into your webs root directory for administrating mysql

Hopefully thats brief enough to get you started.

Matt - matt@islandit.ca

Last time I tried ubuntu server there was an option in the installation prompt to install a pre-configured LAMP installation. I will be testing it again soon and will share my findings.

You could also, goto terminal then perform a sudo apt-get install tasksel
Then after its installed perform a sudo tasksel
A screen will load and allow you to choose LAMP and it will install everything.. Also in the future if you wish to add say samba or openssl etc you can from the menu

phpmyadmin is not needed for a LAMP environment, you just need to install php5 apache2 mysql-server-5
So:
sudo aptitude install php5 apache2 mysql-server-5

and all deps will come out and installed

Depends which version u r using....Ubuntu LAMP server Install the following Versions:
Ubuntu 11.04 (Natty)
Apache 2.2.17
Mysql 5.1.54
PHP 5.3.5