My thanks to you all for your responses ...very informative and helpful. Greatly appreciated... AVC

I just purchased two Bachmann Civil War HO train sets. I am new at this hobby but do have an interest in creating a layout that features a civil war theme. On one side of the layout will be a working yard and the trains will run about ten feet to the other side of the layout. Before I purchase any more trains, am wondering how to power all the track that will be needed in the layout. Each set comes with its own transformer that is DC. Am wondering if these trains can be retrofitted to work on DDC, I think it is called? Is this a part that needs to be put into the train itself?  Will I need a larger transformer too? Thanks ...