Ok you need to create a pivot table
(I'm going to go through this click by click so if anything seems obvious ignore it and don't be offended...its easier to leave in every step that to miss the one step you really needed)
From the menus at the top click on data, then pivot table, The pivot table wizard will pop up, make sure it has selected the data you need it to look at (it can sometimes get confused if you have a title above the column headers), click next.
Now you need to drag the box on the right that has the date header in it (probably "date") and drop it into the row section.
Then do drag *any* other one of the boxes into the data section (it should say "Count of" whatever the header was if it doesn't double click on it and select count).
Click next, make sure that it will put the table in a NEW worksheet and click finish.
The pivot table will show each date and the number of entries for each date...if you need to sort it by the number of entries click in the very top one and select Data|Sort.
I hope this makes sense...feel free to shout and scream at me if it sounds like I'm talking rubbish.