Welcome !! For a first effort it's not bad at all. I like the parchment texture and the brushes are very nice as well. If I can offer you one bit of feedback it is about your rivers. They all seem plausible but they are very wide. It looks as though you used an eraser brush to "cut" them in. That's a good technique but you could try varying the brush scale to get different size rivers. All in all a very good first effort. Keep up the good work and have some rep.