The simplest and easiest way to mount ISO files in Ubuntu is by downloading a program Gmount-iso. You can find it in Synaptic Package Manager

Installing Gmount ISO

Click on System -> Administration -> Synaptic Package Manager. Enter your admin password to proceed.

With the Package Manager open type gmount In the search box and gmountiso (by Crans) should come up. Click on it to mark it for installation. Hit Apply to install it.

When its finished installing you will find Gmount-iso by going to Applications -> System Tools.

Mounting ISO with Gmount ISO

Open Gmount-iso by going to Applications then System Tools.

Create a empty folder on your desktop or Home folder. This is where your mounted ISO files will be placed. You can name it whatever you want just remember where that folder is.

In Gmount-iso the first box (Image File (.ISO)) is the where you put the ISO file. Click Open to browse for the ISO and click Open when finished.

The second box (Mount Point) is where you will point to the empty folder you just created. You do remember where it is right?

With those two inputs filled we can now mount our ISO by clicking Mount. But nothing happened what the hell went wrong? Nothing went wrong, all you need to do now is click on the Jump to button on the bottom and you will jump to the folder you created and in that folder should be the files from the ISO.