[WIP] Kingdom of Adraus and its neighbors

[TrueUndeadHero]

Working on a new mapping project for an upcoming fictional victorian-era fantasy world.

My primary goal is to create a map of the country that my book focuses on, the Kingdom of Adraus.

As I have described it, the Kingdom of Adraus is a largely mountainous, young kingdom which managed to gain its independence following a successful revolutionary movement known as the "100 Day Rebellion", which occurred during a succession crisis of a neighboring empire.

The Kingdom of Adraus surrounds the large inland lake known by many as "The Little Sea (Lutzenmyr)" and as well as the many rivers that surround it, including the Adan River and Jaunc River, which all bleed into an ocean-going bay. The Lutzenmyr sits in a valley between two large ranges. Asides that, I am unsure what else there is to say about the nation that wouldn't just fall into heavy worldbuilding lore.

My main problem comes with the way I wish to do mountains, I wish to represent them as a contour map but I also don't really know how to do that. I have seen maps on how to do it but there aren't many tutorials on it. Right now, I am using Paint.net to paint out an idea but I eventually want to shift to GIMP and make a much more professional-look to it like many of the maps on here. I would like some advice and suggestions on how to do my mouintains properly. I don't really have a good idea on scale, just that the Lutzenmyr is anywhere from 150-200 km and anywhere from 32 to 20 km wide.

Any help would be greatly appreciated please.