Ok, good work on finding out what drives are on the sytstem.
You have two scsii drives both with two partitions.
/dev/sda is the first drive and /dev/sdb is the second drive.
To mount the first partition of the first drive which appears to tbe the smaller of the two (15G)
(can confirm by checking the output of
1. make a directory to act as the mount point, these vary from distribution but you can actually put them anywhere.
in my gentoo system they are under /mnt
2. (usually as root) mount the drive
mount /dev/sda1 /mnt/sda1
mount /dev/sda1 /mnt/oldharddrive
3. access the files
will list all your files.
4. unmount the drive when finished.
5. if its something you want in a permanent setup, look at the /etc/fstab file and add a new line for your drive.