how do I check the integrity of an install-cd after booting

Before booting the LiveCD there was an .iso file burned, where each one has and md5 hash.
e.g.
ubuntu-11.10-alternate-amd64.iso
md5sum
5e427f31e6b10315ada74094e8d5d483

Example.
Lets say the .iso file is in /home/humphrey/Downloads
open a terminal: ctrl+alt+t
Enter:
md5sum /home/humphrey/Downloads/ubuntu-11.10-alternate-amd64.iso

The output should match given md5sum from web page.
https://help.ubuntu.com/community/HowToMD5SUM
https://help.ubuntu.com/community/UbuntuHashes

http://ubuntu-for-humans.blogspot.com/2010/04/how-to-verify-integrity-of-your-ubuntu.html

Sam_,
The question was not about the iso file, but about the cd

actionparsnip,
Sorry, but when I type "sudo mount /dev/hda" the system responds with "special device /dev/hda does not exist".
When I do a dir of /dev there is no /hda listed.
When I do a dir of / Ithere is a cdrom listed, but when I cd there and type "md5sum -c md5sum.txt" the response is "no such file or directory" and indeed when I type dir it just returns the prompt.

Note that I am new to linux

Yes, mount the CD and you can MD5 test it. You cannot mount /dev/hda as it is a drive, not a partition. The CD should automount.

https://help.ubuntu.com/community/Installation/CDIntegrityCheck

actionparsnip,

Yes, the cd does automount: an icon appears on the left and when I click that a panel opens with icons telling me what is on the cd.
Now, how do I do this md5 test?

delance,

The page you referred me to describes how to do the check at *boot*-time.
What I want is to know how to do this check at *run*-time

md5sum -c md5sum.txt

in the folder containing md5sum.txt on the CD

Uh, I really am new to linux so you will need to tell me how to do that

Thanks.

Though permit me to say that for a computer illiterate person this would be impossible to achieve.

Now, somebody please add some instructions to achieve this to https://help.ubuntu.com/community/Installation/CDIntegrityCheck

Thanks actionparsnip, that solved my question.