Modify the /etc/fstab file. Probably better make a backup first.
You can add an entry /dev/xxxxx. But in some cases that designation might change. For example if you remove a drive, one fails or even some changes in the BIOS could probably do it. So I identified the drive by UUID. You can check the UUID with:
sudo vol_id /dev/sda1
Then you can add a line like this to mount the drive at boot:
UUID=8d947571-b0eb-42ab-b482-d4bb093a17c6 /media/sdb1 ext3 defaults 0 0