I'm using Red Hat Advance Server 3 update1
While installing my system, I had maken the partition as following:
/boot 100M primary
SWAP 3000M
/ 72G
Then all my driver space was filled. And I only have one driver in my box.

Now I want to create more partitions, for example, I want to add a new partition named "/setup" and give it 1G space

How to do?
Must I reinstall?

Well, if the drive is filled, you have to resize some partition. Depending on the filesystem you use, it can be done.
How do you plan to use this /setup thing? Is it really important? Can you live without it?

Yes, the directory "/setup" is very important for me.

I'm a newbie on Linux.
I would make clear your meaning.
But I still don't know how to do it.

Would you pls give me your solution in detail procdurces?
Or give me a instruction URL to let me study?

Thank you very much!

??
...but your drive is full - you say...
How would you get additional space by resizing and adding more partitions ?
If / which has a size of 72 GB is full - then only an additional drive will help
If you split the full space in half you have two full spaces of half the size then before!
The only space you could add is by shrinking your swap and adding what came from that as an extra partition - but ths will give 2 - 2,5 GB max - you want to keep some swap, I believe...

do: swapoff

then delete the swap-partition create a new one of your desired size and with what is left over you can create a new partition
then do: mkswap /dev/where_your_swap_is
then change your /etc/fstab to be correct for the new swap
and then: swapon -a

then you can format and use the newly created partition