If you have successfully booted from your memory stick, you should now be looking at the purple Ubuntu boot menu. To start the Ubuntu installer:
Wait a few seconds and Ubuntu will start loading. Otherwise, you can press a key and a boot menu with more options will appear.
Press the F5 key to access universal access options like the screen reader and magnifier.
After a minute or two, an Install window will appear. Select your language from the list to the left of the screen and click Install Ubuntu 10.04.
Follow the instructions on the screen to select your country, timezone and keyboard layout.
When you get to the Prepare disk spacescreen, choose one of the following options to determine how to put Ubuntu on your hard disk:
If you want to keep Windows installed and choose whether to start Windows or Ubuntu each time you start the computer, choose Install them side by side. This is called a dual-boot setup. Use the slider on the colored bar at the bottom of the screen to choose how to share disk space between Windows and Ubuntu (Ubuntu should have at least 4GB of space).
If you want to remove Windows and replace it with Ubuntu, choose Erase and use the entire disk. All of the files on the disk will be deleted before Ubuntu is put on it, so make sure you have backup copies of anything you wanted to keep.
For more complicated disk layouts, choose Specify partitions manually. You can manually add, modify and delete disk partitions using this option.
When you click Forward, you may receive a message saying that the changes will be applied. This normally happens if you resized a partition. If you click Continue, your hard disk will be changed permanently and you won't be able to go back. Make sure you're happy with any changes that you made.
Follow the rest of the instructions to choose a username and password and migrate files and settings from Windows.
Click Install. The installation will begin, and should take 10-20 minutes to complete. When it is finished, choose to restart the computer and then remove your memory stick. Ubuntu should start to load.