Customer Login Script

I need a secure login script that integrates with mysql. The purpose is that each customer can see their account information and are ABLE to edit some fields and NOT ABLE to edit other fields. The registration must be validated with one of the fields which is unique to each client and assigned by the admin (not everybody can register, unless validation goes through). Note: I’m a webpage programmer/designer but I don’t have time to do this script/job. Nevertheless, I’m able to rename and add fields and I can get around code. The design is done already, just need to get done the registration with validation, editable fields and no editable fiels.