How and where to start working with microcontroler

Here are some pointers for you to move ahead.

what are the concept i must know before starting making new project with MCU

You're 2nd year ECE engineering student so the current subject that you should study first would be the micro processor. The most common microprocessor is 8086. And from there you are supposed to study other micro-controllers and processors of different type. If you are learning this in advance then it is helpful if you do understand how the microprocessors and controllers work with other display and devices. You can find that information in the following books - Fundamentals of Microprocessors and MicroControllers by B. Ram and also do read "PIC Microcontroller and Embedded Systems: Using assembly and C for PIC 18". The reason I made this suggestion is that jumping directly on Atmels AT89S52 without knowing other microprocessor and controllers won't be much of help.

where to start learning this mcu

Assuming you know about other microprocessors and controllers, you can check out the below resources for learning AT89S52.

1. Check out the official website, datasheet and pin diagram for the MCU - : http://www.atmel.com/devices/at89s52.aspx

2. Find out how to program this Microcontroller, there are some youtube videos that you can check or check tutorials.- : https://www.youtube.com/watch?v=TdUpOfL4nMA

3. Check out the projects that you can do with this microcontroller board. You can find some books offline. You can also check for such projects online. Check this site for example: http://www.8051projects.info/proj.php?ID=30

4. Get some project kits on ebay based off this MCU. : http://www.ebay.in/sch/i.html?_sacat=0&_nkw=at89s52+programmer&_frs=1

This should give you some headastart and you can design some good projects once you go through the above resources. Do note that you should get in touch with the professor who is likely to guide you on microprocessor and controller. They can guide you on a lot of small things when it comes to troubleshooting which you'll come across while learning and making projects.