There's no quick way of doing this, there's a lot to do, and, fortunately for you, I've touched on this subject in my blog:
Data Driven Login System
The code is in Visual Basic. There's also a bit of SQL in there (to connect to, and read from the database).
Basically all that's being done is we're establishing a connection to the database, connecting to a table in the database and reading the data from a row in that table.
I just realised I haven't written an article on new user registration, so I'm going to do that after I'm finished here.
Hope this helps. Feel free to ask if you need some more help.