In order to create a raid-5 set in Linux, you can do the following:

1. Create partitions using fdisk or parted on your disks. For Raid-5, you need at least 3. If you create the partitions with the type of 0xfd, you don't need to create a mdadm.conf file. mdadm -A -s is ran on system startup and automagically finds these things.
2. mdadm --create /dev/md0 --chunk=128 --level=5 --raid-devices=5 /dev/sd[b,c,d,e,f]1

3. Add the following lines to /etc/mdadm.conf:

DEVICE /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1
ARRAY /dev/md0 level=raid5 num-devices=5 spares=1 UUID=624c89cb:9e2167fe:a8f0cff2:a28fa402 devices=/dev/sdb1,/dev/sdc1,/dev/sdd1,/dev/sde1,/dev/sdf1

4. Use mdadm -As to start up all arrays, use 'cat /dev/mdstat' to give status of current known arrays.

5. Partition /dev/md0, and mount it.

Helpful commands:

mdadm -Ds - shows arrays
mdadm -As - starts arrays