Are you sure you want to create a new table for each new user? Or do you just want to add new users to an already existing table?
If it is the latter you can set defaults for any filed you like in a table, by setting the field default value in the table design view.
If it is the former, there are ways of doing that to, but at this point I can't understand why you would want a new table for each user, your DB would quickly grow to an unmanageable mess.