This is the simplest tutorial i ever met on the internet about installing LAMP.

http://www.howtoforge.com/ubuntu_lamp_for_newbies

One more thing don’t forget to run this command after installing phpmyadmin

sudo ln -s /usr/share/phpmyadmin/ /var/www/phpmyadmin

otherwise u will get a 404 not found error. Actually this command let the browser know the phpmyadmin folder to be in var folder, thought not actually. just link that virtually..