to enter date and time in rails application

I am new learner in rails, i am using rails 3.0.10 . I want to use the
date and and time in my project, please tell me the better way to use
it

Time.now will return the current date and time if that is what you mean.
Have a look at the docs for the Time class.

Colin

Maybe, you should take a look at this

http://api.rubyonrails.org/classes/ActionView/Helpers/DateHelper.html