Is my hard drive erased? How to fix my Powerbook?

Question

I got 2 Powerbook G4's from a company for free but apparently they wipe the HD clean before giving them away. I got a charger for them and then when i turned them on I got a Grey screen with a file in the middle that flashes: Question mark/Mac OS sign/Question Mark/ Mac OS sign...etc. I got a Mac OS 7.6 CD from ebay and i put it in then turned off and on the laptop. It stayed on the same grey screen for a little while then it give me a light blue screen with 2 buttons. on the right a button with a Arrow to the right. and on the left a button with a circular arrow.
after the 2 buttons came i clicked the circular one... mouse turns into a watch and the powerbook is obviously reading the CD again.... after it become a mouse again i clicked the right arrow and nothing happens even though the button "goes in."

Answer 1

No Mac manufactured since about 1997 can run Mac OS 7.6. The earliest Powerbook G4, introduced in January 2001, requires a minimum of Mac OS 9.1 (which is itself obsolete), and the last of the more than two dozen PB G4 models requires at least OS X 10.4.2. To help you figure out which OS X version to buy for your machines, we'll need to know exactly which models they are, beginning with the display sizes and processor speeds. This article should help you begin to identify them:
http://support.apple.com/kb/HT3065
There should be a label inside the battery compartment of each machine containing some of its specifications. If you can find those labels, post back and tell us exactly what each one says, except for the serial numbers — don't post those.