Simple field validation

Hi, I need some simple field validations made to already done html file: [login to view URL] Text in red shows up only after the "submit" button is clicked and red stars show up only next to the missing fields. All fields are mandatory and at least 1 check box. In case the user checks "Android tablet" he should also input text for a phone model. Same goes in case of "Android smartphone" check box. Source files will be provided to the awarded bidder. Please do not bid if you're not planning to start right away. For an experienced programmer this should take less than an hour to make. Thanks, Zveki