The pile of coins represents your Shekels (the currency of many ancient countries, including Carthage). The wheat represents Food, the cloth is Textile and the ingot is Metal. Note you can get 99 MAX of each merchandise type at a time. If touching a city (the red rectangle) press space to trade. You can only sell stuff if it is the stuff a city demands. However, you cannot buy that type of merchandise while that city wants said merchandise. The rest is pretty intuitive. I may add pirates.
This is a good game. However I thought I'd add these two cities (Massalia and Malaga) to make the game a bit more fun, for me at least. I also fixed the hitbox at the Pillars of Hercules. Maybe I'll add more later. I'm not going to tell you how to organise games you like and such, but if you heart this game, you should probably heart the original by @Attalibexerxes, too. He's cool. If you like this game you'll probably like his other games.