i want to download and install internet explorer in Ubuntu

I can't see why you would want internet explorer as there are lots of good browsers available. However Internet explorer can be made to run using Wine. For detailed instructions see here

http://netwrkspider.blogspot.co.uk/2012/05/how-to-install-internet-explorer-on.html

The Internet Explorer does not run well on Ubuntu Linux.
There is not native Linux version, only one for Windows. You are able to run it on the Window emulator "wine" but it has mani limitation and is not very stable then. To make that clear: eben less stable as on Windows.

Now the frankly part: The Internet Explorer is a bad browser. Most Linux used do not miss it at all, infact it is very disliked.

You should have Firefox installed and can install Opera and Chromiun via the Software Center. All three work very well on Ubuntu.

You should provide some information about your system.
This question is not related with Ubuntu or Software Center.

Internet explorer is not Free / Open Source Software and it's not available in Software Center or in any repository for that matter.
There are so many alternatives you may wanna try, most of them are way better than Internet Explorer.
Firefox, Chromium are two examples of those alternatives and both of them are very popular browsers.

But if you insist on using Microsoft's Internet Explorer, you can try to install it via wine. About downloading, you should consult with Microsoft's website.

To install Wine, open a terminal and type:
sudo apt-get install wine

Why do you need Internet Explorer?