How do you make sure the Email field and Confirm Email match?  Use the form validation feature.

1. Click Webform >> Form validation
    
2. You'll see a list of rules (requirements that you want to apply to a field or fields). There is a description for the rule underneath.
    
3. To check if 2 email entries are the same, select
   "Equal values"
   Verifies that all specified components contain equal values (textfield, email, select, hidden) 

4.  On the next page, enter a name in the Rule Name field.  It can be anything you want.  Then select the 2 fields that you want to be checked for equal values: "Email" and "Confirm Email".
    
5. Click "Add Rule" (bottom).