i need to format it what should i do

Normally, one would need a bootable system CD to begin with. Depending upon the iBook model and the operating system, this disc may contain Drive Setup or Disk Utility. To start up from a CD, press the C key. Locate the appropriate utility. Drive Setup and Disk Utility both have many formatting/partitioning options. If you wish to completely erase and overwrite the hard disk, see also the following article:

http://support.apple.com/kb/ht1820

Jan

After erase, there is a matter of choosing a correct Partition Map, then format the HDD.

With a PowerPC (G3/G4/G5) usually that would be the Apple Partition Map, since the

architecture is different than later Intel-based Macs, who require a 'GUID' scheme.

The next choice for the PPC-based iBook, would be to use HFS+ (journaled) for

the format type; especially with a computer that can run OS X. Older models

that can dual-boot OS X and Mac OS 9.2.2 should use this format, too.

The choice is within the Disk Utility selection(s) when booted from the Install-restore

DVD, with Installer's drop-down menus; to choose to use other features instead of

running just the Installer itself.

•About Partition Schemes in Macs:

http://macs.about.com/od/usingyourmac/qt/partition-types.htm

As these older Macs go into Vintage and Obsolete, the information in Apple Support

online is a little harder to find; since focus is more toward new product configurations.

Hopefully you can restore function to the iBook portable without issue.

Good luck & happy computing! 🙂