If by "log in information" you mean that you have a text field that stores the user's account name, you can use one or both of these methods:
Perform a find using Get ( AccountName ) to specify the find criteria:
Go to Layout [staff ( Staff ) ]
Enter Find Mode  --> clear the pause check box
Set Field [Staff::AccountName ; Get ( AccountName ) ]
Perform Find 
Use a relationship.
Define an unstored calculation field, cAccountName as:
Get ( AccountName )
and select "text" as the return type.
Then this relationship:
Table::cAccountName = Staff::AccountName
will allow you to set up a layout based on Table, and you can add fields from Staff --such as to the layout header to show info from the staff table for the current user.