oh blah. I just went into a totlally unecessary responce, and deleted it all. this is simple. when your system boots you'll have a option of going into bios. usually by hitting f2 or delete, tab or something else and holding it when you first power it on or shortly thereafter. Your bios, depending on what bios it is, may have a 'boot' tab or section, in which case you simply often just go in and change the first boot device from your hard drive to your cd drive, hit f10 or something similar and exit and save changes and reboot. it will or should reboot from your cd drive and automatically execute the installation procedure. given I nor no one else knows your bios version or type, or anything else about your system, this is very broad information, but if your system is somewhat modern it should be correct for 99% of the systems out there.
