I need two book covers designed

I have two ebooks in production. They are part of a set (of four). Book 1 and Book 2 are ready to publish and I need covers to be designed. Images for both books have been chosen but need a professional layout, following a style which would be applied to all books in the set - i.e. the individual books would look different (with different images) but have a layout / typography that indicates that they are all part of the same set. The books will only be used as eBooks, will not be printed.