Hi Verytie. If you could define your question a little better it may help to get the answer you require.
My guess If you mean discover a other town, you do that through scouting on the world map. Once discovered, you can do neighbourly help and trade with out fee. When scouting its best to scout in a circle but you can scout directly to an active trader if you wish before returning to scouting in a circle.
you can be related with other players' cities with neighborhoods (with scouting on your map) or with fellowship (you need to join with one fellowship) - no more ways to contact another city on app.
Still - if you play on PC, you can search other players cities by clicking on your ranking number and searching player names there, and so can visit all found cities.