How to add NPCS to your own star city to sell things?
Players do not control any NPCs in this game. You’ll need to create market sell orders yourself.
I’ve created a market, but it doesn’t sell anything
If you are on the test server, players probably won’t buy from you - they’ll buy from the seeded market. The test server isn’t for regular gameplay.
So can’t I have NPCS selling items in my own star city?
Otherwise I would have to go a very long way to buy something because I’m in 0.0
NPCs don’t sell items at player stations - they have very limited buy and sell orders at their own NPC stations (for example, Caldari Navy buys and sells goods at Caldari Navy stations), but those are almost entirely cheap items that make very little profit to move.
The market in EVE is player-centered - players buy items from each other, which come from either their own production efforts or from loot drops from destroyed ships (PC or NPC).
To ‘build a market’, you need a lot of starting capital (isk or goods) and be in an area of space where players have a need for the goods you are trying to sell. You cannot build a structure and then just expect players to take care of making it worth running.