hi Raskat, rep = reputation, its how we show that we appreciate someones work. There is a little icon above your picture showing the 1 rep point I've given you. You can give rep by pushing the star symbol on an entry. You can first give rep points when you have 10 rep yourself, but rep without points are also appreciated

In respons to your waterlines. If you place them on their own layer (or perhaps 3 layers) you can in the top right of the layer menu set the opacity of the layer - lower that to 80% for the line closest to the coast, 60% for the next and 40% for the third (just examples) and you'll get closer to that look