How to make a image file from Pre installed Mac osx ? "PLEASE HELP :("?

You can useCarbon Copy Cloner to copy everything from the working eMac onto the non-working eMac while the working eMac is running. If your eMac will still do target mode into the working one, you can download the above software, select the booted drive as the source drive, and your eMac's drive as the target, however it is possible this will not work.

When you say your eMac crashed, what exactly happened? It is possible that the hard drive in your eMac failed or is failing, so in order to get it running again you would need to replace the hard drive. On the eMac, this repair is somewhat involved, and you have to be very careful because it exposes the CRT, which has several areas which can be extremely dangerous to touch if not properly handled. CRTs retain a great deal of voltage, even when unplugged, sometimes for weeks, and they can give you a nasty shock if you touch them in the wrong place.

Also keep in mind that cloning from the working computer to the non-working computer will ERASE any data that you have stored on that eMac, so if you don't have it backed up anywhere, you may want to attempt that with target mode before proceeding.

Good luck!

Which "other HD" do you mean, the one on the working eMac or the one on the failed unit?

can i boot it of a USB

No, unless I'm misremembering, the eMac cannot boot from USB, only the internal drive or a Firewire hard drive.

Regards.

That's the beauty of CCC. If you boot the non-working emac in target mode, and connect it to the working one, you can clone from the working one, to the drive of your original eMac while the working one is booted up. However, if your drive is failing, even if the clone is successful, and it does boot successfully, it likely won't stay functional for long. And what Dave says is correct, Power PC macs can only boot off of firewire external disks that are formatted with the Apple Partition Map scheme.

A flashing question mark can indicate a corrupted operating system, but the operating system could have easily been corrupted by the drive beginning to fail.

Honestly I would not recommend spending much money or time to fix this machine, especially if you now have access to a functional eMac, but if you find that the drive is failing, and do decide to disassemble, please read up on CRT safety procedures and be extremely careful.