In the server validation behavior, set up 3 validations:
1. Email address is in the email format
Select email address validation type, for the Server Variable, click the lightning bolt icon, and select the email address form element
2. Two password fields match
Select Like Entry validation type, for the server variable, click the lightning bolt icon and select the password form element. Click the plus button to add it to the list of validation, this will open a prompt for you to select the comparison element, select the password confirm field.
3. The email address is not already in the database
Select Unique Database entry validation type, for the server variable, select the email address element. when you click the plus button, select the table to use and the unique column.
Set the key column to the Primary key column, and leave the key value at 0.
to show validation error messages on the page, type the error, select it then go to WebAssist -> Forms -> validation -> Validation show if. select the validation that should fail to show the error message, and click the plus button to add it to the conditions.
One thing to bear in mind wit this is that the validation failure is stored in a session.
this means that if the form fails validation, you browse to another page then come bucket the form page, the validation error messages will still show.
the validation failure wont be cleared until the validation passes.