When you first turn on your computer, you should notice a key to press like DEL or F2 (or something) to get into CMOS setup
Once you see that key (displayed on the screen somewhere)
Press it, within 3seconds, to get into the CMOS setup screen
Now, some old Bios revisions (or computers rather) don't display this key prompt
No doubt yours being one of them!
In that case you would need to work out (possibly through downloading the manual) what the key button press is (ie even if it doesn't show when you first turn on the computer, it still can be pressed)
At last once in CMOS, re-read this thread
edit:
wow give me a moment (ie your edit) I need a few mins to answer