Apologies to all if this is a stupid question but I am new to ArcGIS online! I am trying to create maps of regions of the world where I have shaded certain countries in colours of my choosing. I can find the various base maps and all sorts of overlays, plus can create my own overlays using freehand drawings, for example, but surely there must be overlays for country borders already in existence. I have them for Google Earth but want to create flat maps of large areas of the world, so that won't help me.
Have I missed something really obvious? The answer is probably yes, so please be gentle with me!
Any help would be most appreciated.