How do you find out how many checkboxes have been checked for given Question? For example, you have question called "Hobbies:"with checkbox options of Reading, Biking, Travelling., I want get the count of the hobbies.

Assuming you are using PHP to process your form, when you create your form
give all your checkboxes the same name BUT add the following suffix "[]" -ex:

<form method="post" ...>
<input type="checkbox" name="hobbies[]" value="Reading"/>
<input type="checkbox" name="hobbies[]" value="Biking"/>
<input type="checkbox" name="hobbies[]" value="Traveling"/>
...
</form>

Then when you submit your form then:

if( isset($_POST['hobbies']) )
  echo 'Total Hobbies: '.count($_POST['hobbies']);
else
  echo 'No Hobbies checked';

<form method="post" ...>
<input type="checkbox" name="hobbies[]" value="Reading"/>
<input type="checkbox" name="hobbies[]" value="Biking"/>
<input type="checkbox" name="hobbies[]" value="Traveling"/>
...
</form>