I'm a new user!

Here's my problem:
I'm sort of a newbie to ASP and SQL. I have a login system on my website that uses cookies and queries a database to register and allow users to enter restricted pages. I want to create an SQL statement or perhaps SQL and ASP that will do two things:
1) Show SPECIFIC

user information in an editable form (is this called form population?)
and
2) Allow the user to edit the form and submit it. This will change the information in the database, I assume by using the UPDATE command.
The problems I am really struggling with

:
How do I get the SPECIFIC user's information (note: my asp code uses the code <%=str_users_name%> to display the current user's name on the page. Could this be used?)
How do I insert the database information into the text lines of the form?
What script do I use when the user clicks the submit button? (just a newbie guess, is it <form action="register.asp?step=2" method="POST"> ?

)
Thanks for your help!