You need manequinn model that is to the scale of your map. Then just drag it into map.
You can use one that is included in some starting projects, like top-down.
Or get some free characters from marketplace.
When you have mesh/model you can place it randomly on map, with some simple blueprints. Just get random location, check if map below is street (line trace down, see if hit is on street level) and place character model.