Resize HFS+ Partition

[condor_rl@libero.it]

Hi,

I'm new to Debian on Apple computers.
I would like to install Debian Sarge on PowerBook G4 12" with 1,33Ghz
Processor.
I give you information on CPU Speed so you can better identify the model I'm
speeking about... Because I do not know how to identify the model.

My problem is made of the fact I have one HFS+ partition on my Hard
Drive, and the partiion has the size of the entire hard-drive, so there
is no free-space.
So I need to resize the HFS+ partition to free space and create at least
a Linux partition.
..But I would like, I need, some advices, about the right tool and the
procedure to complete this critical taskd.. :)  

Thanks
Lorenzo