Adding a new disk on OpenBSD

First you need to use fdisk tool.
fdisk wd1
this will add new Master Boot Record data into MRB

then use disklabel to create partitions
disklabel -E wd1
use a to add partitions
use A to create automatic partitions
use p to print partition data.

then create the new filesystem
newfs wd1a

and finally mount the disk somewhere
mount /dev/wd1a /newDisc

optionally to have this disk mounted on each startup add the following line to etc/fstab

/dev/wd1a /newDisc ffs 1 1

wd1a - is our IDE primary master disc
wd = ide