Hello and welcome to the Cartographer's Guild, Twistomud!
That's the sort of information that you can choose to either display on the map, or leave it out. Even if you don't spell it out, it's generally a good idea to figure out for yourself how large the area being shown on the map is, so that you have some general idea of the distances.
First, you should decide the dimensions of the area your map will represent. Eg. 50km x 20km. Once you know that, decide the maximum size of the image you're prepared to handle, in terms of pixels. Eg. 12,000 pixels wide/high. Then you just divide this maximum value by the greater of the dimensions of the mapped area: 12,000px/50km = 240px/km. This number is the ratio used for your map. Now that you know the ratio, you can multiply the smaller area dimension by it to find the respective pixel size for the image: 20km x 240px/km = 4,800px.
That is called a scale. The numbers above the line show the distance (in this case, in miles) over the mapped area that corresponds to the length of the line up to that number, starting from the 0. If you put a scale on your map, you need to make sure that it's correctly sized - that is, it's length in pixels actually corresponds to the labeled distance.
You can probably find a menu command to turn the image into "grayscale" in whatever software you're using. If you actually want to make the map into black&white lineart, you'll need to clear or hide all the elevation clouds/texturing. This will be easier if you're using multiple layers when editing the map picture (and save it in a format that preserves the layers).
A good first map. There seems to be a river (the only one on the map?) on the central island that runs across mountain ranges. That's impossible, because water always runs downhill. You might want to search this forum for tips on how to place rivers - there should be plenty of information on that subject.