First of all, welcome to the forums. I also wish you good luck on your ambition project. Having that said, I don't know if you have settled on using a particular program to produce maps with but the most used ones around here are GIMP (free), Photoshop (big price tag) and Campaign Cartographer 3 (small price tag). Of course there are more but these are the more popular ones to my knowing. I don't have any experience with the GIMP as I've been a PS addict mostly, next to a little bit of CC3 experience. The tutorial section contains quite some instructions on how to work with either the GIMP or Photoshop for map making and of course there's this simple yet helpful guide on how to produce a world map from scratch (even though it barely touches the surface on the subject, just take a look at some of the threads around here on climate or this guide).

As for your world map (assuming it shows all land) it looks land is far more present than I would have it but you're the boss. I don't know how to read your climate map as there is no legend included.