There are a number of options depending on how you have set up your db and how 'secure' you need to be but the easiest would be to hide your your tables and queries - right click, select properties and tick the hidden box - and make sure the user has not ticked the 'show hidden' box in the db properties.
Next alternative is to prefix all tables and queries with 'Usys' which will then hide them as if they were system tables (or queries).
After that you are into hiding the ribbon and/or the Access window - there are plenty of posts on this forum for you to refer to.
