Format your computer.
Format your storage device to create bootable installation media (Typically a flash drive) .
Download the latest Ubuntu server installation file.
Write the Ubuntu server installation file unto the prepared flash drive.
Insert the flash drive in your computer and start up your computer.
Select the option to start the computer from the flash drive.
Select to run and install Ubuntu server.
Follow the prompts and take note of all you selected settings, usernames and passwords.
Restart your computer after the installation.
Connect your Computer to a network via a LAN cable or WiFi.
Update your computer.
Install LAMP.