Defragmenting?

On a Mac (iBook), how do we

1) defragment the main harddrive?
2) make a backup of the entire harddrive or certain folders? Would like to burn the backup.
3) optimize?
4) Any other procedure you guys take on a monthly basis?

there is no 1 or 3 on macs.
only procedure I do on a monthly basis is just repair my disk permissions in the disk utility (Applications --> Utilities)

As for the backup i am not sure since i just have an external harddrive with all my important stuff on

What I've used is the OS 9 versions of DiskWarrior and TechToolPro to defrag my OS X volume. Works great.

As far as backup…
If you want a snapshot of your OS X volume then use Carbon Copy Cloner. If you just want files then SilverKeeper is a good backup application.

Using Carbon Copy Cloner, I burn a backup of my OS X volume directly to DVD.

Backups

I use CCC (Carbon Copy Cloner) every once, and a while, but it takes a while to work, so I mostly use Backup2 that came with my .Mac subscription, it comes pre-installed with critical backups folders, and allows you to select any others you'd like.