celeron 500 in a hp pavilion 6573z

[neo62896]

where do I start to overclock this
how do I access the bios to alter the settings
please help

[Tim-]

I doubt that the bios will allow overclocking this machine. HP (and most "Name" brands) go to great lengths to make sure that you can't. They don't want you to buy the cheap model, and tweak it to outperform the expensive one.

Accessing the bios is usually done by pressing the delete key, or F10 during the boot cycle. Watch the screen closely when you power it on, and there should be an option to enter the bios setting mode.