Newbie question on recovering an offline datafile

This is not an urgent situation as this only involves a test instance of the database. Here is the situation. I refresh our TEST and DVLP instances of our production database through a series of scripts. On our production database (8i) I added a new datafile to a tablespace. When I do this I manually add the new datafile definition to a script that creates the new control files for the refreshed TEST or DVLP database. Well this script wasn't updated prior to the last refresh of the TEST datasbase.

At this point I receive error messages from our concurrent manager (we run Oracle Apps 10.7) containing ORA-376 and ORA-1111 errors. I found that the database didn't know what to do with the references to the new datafile and took it offline. I found the offending datafile and renamed it in the database, but now I can't bring it back online. It appears that the datafile needs to be recovered. I can easily solve the problem by refreshing the TEST database from last night's backup of the production database, but I would rather use this as a learning exercise. Can anyone guide me through the steps needed to resolve this issue?

Thank You,
David Jaeger

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