The shortest and easiest path is to install VMWare (or VirtualBox) on the Win7 partition and complete the configuration as was done in the online class (install Ubuntu, Java, and Hadoop).

Ubuntu should have only one code base. The gnome desktop you have just sits on top of the Ubuntu Linux base code. That being said, you may be missing other packages not necessary for the desktop, like OpenSSH. Better to install Ubuntu in a VM, otherwise you may have to start a fresh Ubuntu install to ensure that you get the correct packages. This is just my opinion. Others may have a different way for you to approach this.

Paul

P.S. I have Ubuntu Server running a light, stripped down Desktop, in VirtualBox.

Hi Vishal,
Yes, is it possible to convert desktop version to server version.
Please follow the below link to convert ubuntu desktop to ubuntu server:
http://askubuntu.com/questions/511463/can-i-convert-ubuntu-desktop-14-04-to-server

Thanks, Hope this helps.

Thanks for the update, Abhijit -- very helpful.

@Paul: Hi Paul, thanks for your response and help. I really appreciate your info. But here is the problem, I have 32 bit processor with only 1 GB RAM at my disposal, which makes it impossible to install VMware on it. That's exactly the reason I have installed ubuntu and trying to make work in it directly, so it will require less hardware resources. Well, I should have mentioned my system configuration in question as well, my apologies for that. All in all, I cannot install VMware due to my hardware insufficiency, and I cannot screw up with my existing Windows 7 OS. I cannot even install ubuntu on different partition. I have managed to install and run ubuntu desktop in the same drive as windows 7, all I need to do now is to make it a server some how. But I don't know how to do that. See if you could help. Thanks again.

@Abhijit: Thanks for your support too. But I have already been through askubuntu.com even before asking this question here. I have already made my google searches too. And I have mentioned in my question that I am not able to install tasksel in the first place in my ubuntu. This kind of makes it impossible to install server image. So please help me with that. What should I do when I am not able to install the packages like ssh or tasksel in ubuntu?

@Abhijit: Hi Abhijit, I just created my own AWS EC2 account on amazon and I created my own Ubuntu server on it. I will be able to practice on it now onwards. It means there is no issue at amazon's end. I think you need to check whether dezyre's ec2 instance is working properly or not. And in case, if any other student is facing the same issue, I would recommend them to create their own instance on the EC2 cloud. Its free of cost.

Hi Vishal,
There is never be the issue with the Amazon. We are setting up the cluster for Hadoop 2.
You are currently using hadoop-1.2.1.
Hadoop 2 required lots of resources and machines as well.
We are aware of the free service that amazon provide for demo with limited resources.
Thanks.