Welcome to the Guild Tierra Gloriosa! Sometime ago a member here created maps for an anti-deluvian ancient world for a book they were writing, but I believe you have the distinction of being the first member (at least that I've heard of) who is creating them for your own Bible. Great project! There are a number of resources here to get you started. The tutorials section ought to be the first place you stop. You could spend literally days browsing through all of the tutorials though. If you are looking for tutorials specific to Adobe Photoshop I'd recommend having a look at the "Tutorials in PDF Format" sticky at the top of the section. It offers a breakdown of many tutorials by software. I wish you all the best in this new project.