aspx pages allow you use code behind pages written in VB or C#. In the aspx page (which is mostly like a normal html page), you would lay out the controls that get things like the query fields and passwords from the user. Each control is associated with an event handler, which means that when you do something to the control, a method with says handles <event> is called. In that event handler you do what you want.

The event handlers are, as I said written in VB or C#. Both provide methods for opening databases (Access or otherwise), making queries, and suchlike. For instance to open a database you code () (where Connection is a Connection object representing your database). Most of this is done with calling the appropriate methods on .NET database objects.

When you've got something to send back to the user, you give it a name that appears in your aspx page, and/or invoke an event that will display it. In the aspx you use names defined in the code behind in tha format <%name%>.

That's it in short. To get the details like sytax and supported objects look at W3C's ASP.NET tutorial, MSDN's ASP reference and MSDN's VB reference