You need to mount the partition where you have the files. Was the second disk in your machine when you installed Linux? If yes, look into /mnt directory. In one of dirs inside /mnt there may be files you're searching for.
If not, you need to create a directory when you mount the partition. For example, it may be /mnt/files. Create the directory (as root). Then you need to find out Linux name of the partition. The name is something like /dev/hdb1. 'b' means second disk (primary slave) where '1' means partition number (so /dev/hdb1 is first partition on primary slave drive, /dev/hdc1 on secondary master and so on). If you don't know the full name, open a terminal (as root) and run
(if it's primary master)
to list partitions and
Look at the table printed by fdisk. You should be able to find out which partition you'd like to access. Then run
mount -t vfat /dev/hdb1 /mnt/dirname
replace /dev/hdb1 with the right value and use right directory (created before) instead of /mnt/dirname
Now there should be your files inside /mnt/dirname . When you don't need them, use
to unmount the partition (it doesn't remove the files).