You spotted highways in imagery. You correctly assessed the width of the western two highways but the eastern one is in fact wide enough for a car evidenced by the tracks on the ground. For the puropses of this project please consider whether the highways you're mapping connect settlements; those which don't are beyond the scope of the project. 

When mapping highways, please trace their shape accurately. Accurate highways aid navigation and prevent issues like data overlaps. Zoom in so that you can see the width of the highway. The lines you trace to represent highways should follow their centre; so add more nodes the more they curve and click at the start and end of straight sections, as a rule of thumb keep the lines you trace within the width of the highway you're mapping. Following tracks or road markings can help.If the highway fans out into several close alternative paths to the same destination then you only need to trace the median or what looks like the most used route. 

Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/