For a start I'm knot sure how you are going to insert into the database table with only one text box - I'm assuming you need to be able to add an author and book to the database.
You already have a database connection done so the only thing left is looking into how to UPDATE, INSERT and DELETE in a database.
I'm not going to provide you with code (it sounds a lot like a uni assignment to me) but for the insertion for example, you need to connect to the database and then add the data you want to insert into your SQL query:
INSERT INTO table_name VALUES(value1, value2, value3, etc)
Then execute the command and you should be done. You will find plenty of tutorials that explain ado.net and SQL online. Once you have had a crack at it and got some actual code to post up we can give more specific advice.