1. The number of pages in the book you want to design must be a multiple of 4.
2. Templates are available online, and there are many vector diagrams to choose from, but the overall style should be adjusted according to the content and the color tone that your girlfriend likes.
This matter has nothing to do with the publishing house.
Generally, it takes a lot of time to make this thing. If you have no art foundation or are not skilled in software, it is basically impossible to make it. I suggest that you can make an e-book, which is simple without printing. Just use the software IEBOOK.