I'll explain here how to "mount" a iso-file.

Files you can mount are "iso-files", iso-files are virtual CD's which you can put in a virtual driver. If you did that, you can open the CD and install it etc.

You can make your own iso-files too, but the most files are downloadable...

I use the iso-file of Assassins Creed Brotherhood as example but it works with any other .iso

 Recommed items:

- Daemon Tools (Light) http://www.daemon-tools.cc/eng/products/dtLite

- An iso-file 

Step 1:

Open Daemon Tools and the map with your downloaded files

Move the .iso file to one of the virtual drivers (follow the line).

Now it's mounted and you can open it.

Step 2: