Read tutorials you need to learn in order to properly install and upgrade Ubuntu on your computer or Laptop.

Burning the Ubuntu install CD or Making a bootable USB flash drive install flash drive. 

Burn Ubuntu 9.04 CD image on to a CD
Learn how to use Deep Burner Free edition for windows to burn Ubuntu 9.04 CD image onto a CD-r, or DVD-R, so you can use the CD to install Ubuntu on your PC.

Install Ubuntu 9.04 on a flash drive
Learn how to install Ubuntu 9.04 on a flash drive, so you can start Ubuntu on any computer that can boot from USB drives.

Installing Ubuntu and upgrading it.

Clean Install and Update Ubuntu 8.10 tutorial
Learn how to Install and upgrade Ubuntu 8.10 Desktop Edition.

Clean Install Ubuntu 9.04 Desktop/Laptop edition from  a Ubuntu 9.04 installation CD
Learn how to do a clean installation of Ubuntu 9.04 from a installation CD which you will use to start your computer.  

Update Ubuntu 9.04
Learn how to update Ubuntu 9.04 with update manager.