In this installation guide I am going to be using the Ubuntu 10.04 (Lucid Lynx) LiveCD, but it should easily translate to any distribution.
If you dont have a CD/DVD drive and your BIOS supports booting from USB you can create a LiveUSB and use that as the installation medium.
1.
If youre using a CD: Put the Ubuntu CD into the
CD/DVD-drive and restart the computer. You should see a welcome screen
prompting you to choose your language and giving you the option to
install Ubuntu or try it from the CD.
If you dont get this menu, read Ubuntus
booting From the CD guide for more information.2.
If youre using a USB drive: Most newer computers
can boot from USB. You should see a welcome screen prompting you to
choose your language and giving you the option to install Ubuntu or try
it from the CD.
If your computer does not automatically do so, you might need to edit
the BIOS settings. Restart your computer, and watch for a message
telling you which key to press to enter the Boot device selection
screen and select CD/USB from there, if you dont see this message you
will need to enter the BIOS setup. It will usually be one of DEL, F1,
F2, ESC or F10. Press this key while your computer is booting to edit
your BIOS settings.
You need to edit the Boot Order. Depending on your computer, and how
your USB key was formatted, you should see an entry for removable
drive or USB media. Move this to the top of the list to force the
computer to attempt to boot from USB before booting from the hard disk.
Save your changes and continue.
3. Choose your preferred language and click on Install Ubuntu 10.04′
4. Select your location and click Forward to proceed.
5. Select your preferred keyboard layout
6. You can install Ubuntu alongside your current system or instead of
it. Use this screen to choose your installation preferences.
Using the install side by side option will install Ubuntu on the
free space in your computer. You can use the slider to allocate more or
less space.
7. Enter your account and password details
8. Review your options and click on Install
9. Learn more about Ubuntu while the system installs
Or make a cup of tea!
10. Restart and enjoy Ubuntu!