[iBook] How do I set up a new username and password

[Sean Finnegan]

I have mislaid my username and password.

I am asked for these when I attempt to download the latest software  
updates.

Would like to know how to set up a new username and password.

I have an iBook G4
Mac OS X Version 10.4.11
   Machine Model:	PowerBook6,5
   CPU Type:	PowerPC G4  (1.2)
   Number Of CPUs:	1
   CPU Speed:	1.33 GHz
   L2 Cache (per CPU):	512 KB
   Memory:	512 MB
   Bus Speed:	133 MHz
   Boot ROM Version:	4.8.7f1

All help appreciated

Regards

Sean