hit "Delete" key when you power on your computer, you can then go into BIOS screen, choose the right sub-screen (follow the screen and their options in your manual), Remember to save and exit for the changes to be effective.
And you have to hook up the computer before you can change all of those (CPU, RAM, Video, Hard drive), this jumperless design is easy to work (all done in the BIOS screen). I remember only one jumper to set the FSB between 100/133 is needed.
(if you use Althon, XP, etc pick 133).