In this tutorial shows you how to validate form using Macromedia Dreamweaver, it will show alert box when someone press submit button and forgot to fill your requied fields.
Click on table and you will see form tag appeared then click to select it
Open tag inspector panel (Press F9)
At your panel bar open your tag inspector panel (press F9 or window > Tag Inapector)
Select tab "Behaviors"
Select onSubmit
Click on a plus sign then select "Validate Form"
Validate form
In this step in Name fields box select what field you don't want to be blank then tick "Required" and choose what you accept.
Test in your web browser
Press submit button without insert any value in form fields you will see this alert box.