I need help developing a web site with a database

Sure, this makes perfect sense.
You can download ASPRunnerPro and start building this kind of project.
It looks like you need to use Advnaced Security mode "Users can see and edit their own data only".

Sure, this makes perfect sense.

Thanks Sergey! I have noted the basic requirements down as follows...(of course then I noticed you answered the post!). In any case I will still cut and paste what I spent the last 10 minutes on!

Web Application
Summary:
The software I want to develop (at a basic level) does the following:
My customers can log in and input information into a "web form".
My company receives notification that a new or revised record has been created or updated.
My employee(s) then open the record, review and then will add information to other fields that the customer cannot see.
My company now has a record and ability to see all the fields.
My company can now automatically insert some of the fields into an invoice, itinerary or any other word document / .pdf we have as a template.
We can now make the data "web enabled" so the customer can view specific records that meet specific criteria.
When certain conditions are met, an email is sent automatically to pre-populated address(es) with specific information.
All of the above "looks" like the customer's and employees are doing it on the internet.
Questions:
Which program do I need to buy to accomplish this?

How do I link it to a website?

How do I ensure security?

You need to purchase ASPRunnerPro or PHPRunner.

Get ASPRunnerPro if you use MS Access or SQL Server, get PHPRunner in other case.
Security options can be set on Security screen.