Welcome to the Guild Onna (and yes, some of us here do read the newbie posts). Well you have certainly come to the right place to learn digital cartography. We have many authors come unsure of their skills but desirous of making maps. Many of them walk away amazed at what they are capable of achieving after trying out a tutorial or two. So that would be my recommendation to you. There are tons of tutorials for Photoshop and GIMP here. Pick a few that have results that you like and try them out. If you have questions, post up a WIP and ask for help. This is a friendly and knowledgeable community and you'll likely receive the help you need.

Cheers,
-Arsheesh