Google Spreadsheets: Counting entries on a specific date

Hi guys,


I'm an Excel novice and am trying to figure out how to perform this function on Google Spreadsheets (which appears to be slightly different to Excel);

Calculate the sum of the numbers in column D that occur on the 10th January 2014?

And also;
Calculate the sum of the numbers in column D that occur between 9am and 10am on the 10th January 2014.

I don't know if this is even possible on Google, but any help would be very much appreciated.

Cheers,
Aryan

I should add, I have a list of Dates in column B,
and a list of Times in Column E