Welcome to the Guild Elliespot! There are several threads here on the topic of evaluating different forms of map-making software (or software that can be used for that purpose). My own recommendation would be to check out GIMP, a free raster based program similar to Photoshop. You won't have to pay a penny and the program is fairly powerful. Also, there are several great GIMP tutorials here. Best of luck on your project.

Cheers,
-Arsheesh