to link a table (in Access 2007 - i don't have and not used previous versions) in another database, go to the "External Data" ribbon. In the "Import" section, click on "Access", then choose the option "Link to the data source by creating a linked table", then browse for that database that you want to access the table from. click OK.
now access will display all the tables in that other database. select as many as you like, click ok, and you will now see an icon for that table in your asset pane, but unlike the other table icons in your database, this one will have a little arrow on it, indicating it's a linked, not resident, table.
HTH
edit: if you want to remove the link, just click on the table and press your keyboard delete button. access will then ask if you want to break the link.
edit2: this is, as far as i'm aware, how you 'link' a "front end" (FE) database to a "back end" (BE) database - sometimes known as a "split" database. a database is often split when multiple users are intended (most popularly, a BE resides on a communal server and each user gets a copy of the FE on their own machine - there are also various ways to update FEs in this config), though some people make a "front" and "back" end for single users too.
