Linux desktop
 

can you please tell me after installing ubuntu desktop 12.04.2 which server applications should i download and how? can we install both ubuntu server as well as ubuntu desktop? i am a complete newbie so please help...

Obviously, you should install those that you need, nothing else would make sense. To install software on an Ubuntu system you can use the Software Center, the Synaptic package manager (not installed by default) or one of the command-line tools, like apt-get or aptitude.
Both, the server and the desktop edition, are only a base Linux system with different packages installed. You can install a desktop on the server edition and server packages on the desktop edition without a problem.

You can get into the software manager in Ubuntu and look into the server section to look at server downloads that might help you out. The best policy in my opion is careful experimentation, that is how I've learned about 50% of what I know about computers. So, feel free to make as many downloads as you want and try as many as you want to discover what is best for you.:)

Be sure to ask if you need any more help.

Tobis, don't forget that the OP is a total newbie in Linux. The OP was merely trying to figure out which of the plethora of server applications would suit his needs best.....all of those choices can be quite confusing for a newbie. You said at the beginning that the OP should install what he needed, but that is just the thing, he doesn't know what he needs.

What type of server are you planning to have? File server, home media server, web server?

This link from Ubuntu might help: https://help.ubuntu.com/8.04/serverguide/

If you need to install a server, regardless of the OS, you need to know which services you need. It doesn't matter at all if the OP is new to Linux, the common services have the same name on Windows and Linux.