A Split database usually consists of a Back-end database which contains all the data tables (and nothing else) and a Front-end database with all the Forms, Queries, Reports AND links to the back-end tables. If you have a database which contains "...a bunch of linked tables in it and not much else" you either do not have all the split database OR (most likely) the forms, queries and reports have all been hidden. To check for hidden objects, go to Tools|Options|View and make sure the Hidden Objects and System Objects checkboxes are ticked.
As for a book or tutorial on database splitting, read the Access On-line Help topic Split an Access database and do a keyword search on this site for "Splitting a database". Also check out the FAQ section.
The rationale for a split database is basically to allow multiple users to access current data at the same time, and to allow system development without affecting those same users until you are ready to roll out any changes.
To unsplit a database:
1. Make sure you know where the tables are located. Use the Linked Table Manager to find this.
2. Delete all the links to the tables from your Front-End database.
3. Use Files|Get External Data|Import to import the tables from the Back-end to the Front-End.
Your application is now unsplit.
HTH
Lightning