How to encrypt the whole Access database with vb.net

Why? There's no point to it.
 
In order to use it, you would have to decrypt the database for the life of the application session. This completely strips your database of the encryption "protection" allowing anyone to copy/open the database during the time your app is running.
 
Then, when your app is done with the database, you'd have to re-encrypt it.
 
But, what happens if your app crashes when the database is unencrypted?? There that data sits, out in the open.
 
The bottom line is if data security is a concern, don't use Access databases.