I did this awhile back when I was working .. unemployed right now
First off .. within Access you can "split" your database... my database had nice forms and buttons for about 30-50 employees to enter and change data in. When you split the database.. you will have 2 parts. The actual Table data and the forms, reports etc. Think of the Forms / Reports etc as the Front End... where users can access the gui's and buttons.. etc. Think of the Table data as the Back End... where just the raw tables are stored.
Now that the Database is "split" ...whichever computer (within your local network) you put the Front End on will have access back to the Back End / table data. Note: If you move the Back End anywhere else on your system (besides copying it somewhere else for a backup) .. the Front Ends will not find it.
If you are worried about secuity from the front end. Then you should run the Users and Groups Security Wizards under the Tools Menu.
Hope this helps.
Taz