Susan once you split the database (good job by the way!) as you can see you have a whole new set of features good and bad.
One you can push out a working copy that people can continue to work with and still have a development copy that you can play with.  That is the good.  
The 'bad' is #1 if you make changes to the copy of your dev back end you also will have to remember to make the change to your production copy.  #2 regarding the front end, if you make add a linked table to your front end (or any other changes to forms, reports, queries, etc.) it is only for that copy of the FE.  In order to make it available to everyone you must give each user an updated copy of the FE.
This is both good and bad because you can use it kind of like a simple security if you will.  You could have one version for the warehouse and another version for accounting, yet another for management. (though as you get more advanced Richard will show how to get past that.)

Back to your question. You need to use the linked table manager to add in the linked table to your FE then redistribute the file to the individual users.  See the Relink Tables.
Also covered extensively in Access Developer 33

You might want to look into the Access Updater as well.
That will show you how to automatically update your users if there is a change made.