I think it looks like a good start as well.

The grid mentioned by JT is a good idea, but if it is a road side battle, you need to figure out the route of the road, then/or before figure out what sort of scale you want. This would help determine what other features (and size) and details get added to it later. What I am talking about when I mention scale is are you planning on using the map for figures, or as a representation of the land, and just marking the character locations on it. This would depend a lot on how many people (combatants) are going to be on the map, and whether or not you want this to be a bit of a running battle that could move away from the roadside...

Actually, rereading your original post, I noticed that you want it for VT gaming...definitely put in a grid (size of grid i believe for VT is usually 50px or 100px per 5 feet. Some one else with ANY knowledge of VT maps should be able to correct me on that though.), but you still need to figure out the route.

As for the tools, yes having a tablet is helpful when doing digital graphics, and yes it does take some getting used to....and if knowledge of gimp is a problem...we DO have plenty of tuts on Gimp...