Are there any NPC settlements that have vendors where you can sell your loot, buy stuff, and get healed up? In the other Fallout games it seems like you found these right away, but I can't find them in this game. One of the loading screen tooltips says that most of the settlements have doctors that can heal radiation and crippled limbs, but I can't find these - I can just find the empty settlement locations that you have to build on. Where is the first NPC settlement that you get to?
Here are some merchants you can sell stuff to:
Also vendors will visit your settlements (such as sanctuary) on occasion.
You will get a marker for Diamond City relatively early on during the quest:
When Freedom Calls