Hey brother!its just a simple task just watch the words mentioned in box and fill it correctly,if error will occur again you will get a new captcha box.

Hello,
You can fill captcha box while applying for any engineering entrance exam by filling the letters mentioned in the right  hand side or in below in the shape of rectangular box.You can eadily understand what that letters/numbers are and thus you  can fill it easily.
Good luck.

Dear King
Due to security reasons, every website will have some captcha and you need to enter those letters in the box or if you won't able to recognise it then you can refresh that too.
All the best.