If you want RAID you should probably read up on the RAID How-To's over at tldp.org so you have some idea of what you're getting into.
As for partitioning and using space on your drive it more or less goes like this;
1) Partition the drive and assign partition types (linux, linux swap, raid autodetect, fat32, etc...)
2) format the partitions with your choice of mk2fs, mke3fs, mkreiserfs, etc...
3) mount the partitions with the mount command or by adding the required mount device/points/options line in /etc/fstab.