Javascript for validating form

I need a Javascript to validate a form. In attach you'll find the form, all fields that have the sign "*" are bound to be filled. If they are not filled, once clicking the continue button ([login to view URL]) a windows message should appear saying "Please fill field ....". Notice that different fields appear according to the coutry of residence (field "Residencia") and so the fields to validate depends on the country. Provider will have 2 days to complete the project. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Installation package that will install the software (in ready-to-run condition) on the platform(s) specified in this bid request. 3) Complete ownership and distribution copyrights to all work purchased. ## Platform Javascript / ASP