For you as a publisher getting started is easy, as most of this will feel very familiar to you. You already layout your books in a layout program like Adobe InDesign and make your own cover designs. When you print books via your offset printer you give him high-resolution PDF files from which he makes plates and prints your books.
For POD production of your books essentially the same file preparation process is used so when you have your files most of the hard work is done! Instead of giving your printer a flash drive with your files or uploading the files to his ftp site you will be guided through a step-by-step process to give us some basic information about the book and upload your files for the production of your book. For those that have worked with design programs, where they need to set up sizes etc., this process will feel very natural and is not complicated.