I wasn't paying to much attention when I was partitioning my disk while installing red hat 9. Now, I'm out of space on my root partition. I was wondering, is there a way to change partition sizes without destroying data in linux? More specifically, decrease the size of /usr by 1GB and then increase the size of / by 1GB without destroying data? Also, I'm a noob, so I would appreciate it if you dumbed the answer down.

Not unless you're using Logical Volume Management, which you're probably not because you would have had to use the Expert Partitioning option to set it up. There may be some tools like the PartitionMagic program for the MS world around, but I don't know about them. There's actually a simple way to solve this problem without re-partitioning, though.

Identify some subdirectory (or set of subdirectories) of / that occupies around 1GB and isn't needed at boot time. /var or /opt are good candidates. Take your system down to single-user mode (use "telinit 1" to do that), log in as root, and move the directory (or directories) into /usr somewhere. For example: "mv /opt /usr/opt". Then make a symbolic link from the old place to the new place so that the directory will still appear to be where it used to be (eg. "ln -s /usr/opt /opt"). Bring your system back to the usual runlevel 5 ("telinit 5") and everything should be as you want it to be.

GNU Parted can nondestructively resize partitions. It's probably on your RH9 cd.