linux - Upgrade to ubuntu 13.04 from 12.04 with iso image

I have ubuntu 12.04 installed on my system. I want to upgrade it to ubuntu 13.04. I want to do this upgrade using an iso image of ubuntu 13.04.

I tried this Solution

But it didn't work for me.

After running these command I didn't get any alerts about updating. Also I don't understand the gksu part of the solution.

Here are the steps I tried:

sudo mount -t iso9660 -o loop PATH/TO/ISO /cdrom

then

sudo /cdrom/cdromupgrade

Read more: http://linuxpoison.blogspot.tw/2011/06/how-to-upgrade-ubuntu-using-alternate.html#ixzz2SFMqlOPx

I also wanted to know, If I can do this using a networked computer. By this I mean the iso file is on some other computer.

Thank you.