MAC G4 won't boot - Blue screen appears

My emac desktop comes on and has a blue screen.  I don't know what to do.

Hi Sorry to hear you are having troubles,You will need a firewire 400 cableOK, first thing you must do is reboot the eMac in TARGET mode, this means it will be recognized as an external disk. To get the eMac in TARGET mode, you must be sure the eMac is turned OFF and has a functioning keyboard connected.Power on the eMac and very very rapidly press the ( T ) key on the keyboard, be sure the caps lock button is not pressed. If all goes well, you will see the firewire logo appear larger than life on the screen.( If you are unable to get into TARGET mode, it is highly probable that the mother board of the internal hard drive is damaged and preventing the eMac from entering TARGET mode, sorry, that's the end of the line..)Once you enter TARGET mode on the eMac, connect the firewire cable to your G4 PowerBook, you can do this either while it is running or when it is off and then turn it on.
You should see the volume of your eMac internal hard drive appear on the PowerBook desktop...sometimes you need to open Disk Utilities and repair or mount the drive manually.If this all works well, copy the required files directly to your PowerBook...After that, power off both machines, disconnect them and reboot the eMac using a CD or DVD to reformat and reinstall a new system.