Well, there should be no need to manually mount anything. If the disk is
there, it should be visible on your desktop, since all attached disks
(other than the local linux disk) and usb drives are automatically
mounted and appear as desktop icons.

If the disk doesn't appear, then something may be wrong with it. Did
ubuntu see it during the install?

If you look in Places on the top panel you should see it and if it has
windows on it, it may show up as "Boot". A click on it will mount it
and it will show up on the desktop.

Open the file manager and click on the drive listed on the left side.
That will display the contents and open it. If it doesn't appear there
it may not be properly installed. Check the jumpers etc. You can
verify that it is indeed properly install using a live CD for any
distribution of Linux.

Ubuntu has good support for NTFS partitions and it will appear no
different than a native ext4 partition. You can copy back and forth at
will using the right click menu and several other methods.

(1) is there data on the second drive?
(2) what is the device name of the first drive - should be something
like /dev/hda1

Click on 'Places' at the top left of the screen and your second HD
should show in the list underneath the 'Computer' entry with the name
that it was given when formatted originally. Click on it to mount and
view the contents then you can copy/past to and fro all you want :-)

Useful tip - when you have the drive content showing ( or anything
else being viewed in the file manager ) if you Right Click on a folder
or any item in the folder list on the left you get an 'Open in a new
tab' option .... yes, file manager has tabs just like a browser !!

Ubuntu doesn't automatically mount permanently installed HD's
unless you tell it to do so ( either using the mount manager in 'Disc
Utility' or adding manually from the command line ), or has
added this functionality.

Yes Ubuntu seen the harddrive on install.