This page of Anno 1800 game guide focuses on gathering resources. You will find the most important pieces of information below.
Gathered resources can be divided into two categories: complex products, which are the results of longer production chains, and natural resources. We will focus on the latter type first - Every island has some natural resources. Information about them can be found on the minimap. For instance, the above picture shows that the city has e.g. two sources of clay or iron. Furthermore, soil allows you to grow potatoes, grain and hop. You should also draw your attention to the fact that your island is surrounded by some small islands - you will find some natural resources there.
Products that are more complex are usually harder to acquire. You will often need to build several facilities to produce new materials, which can finally be used to make e.g. soap. The above picture shows that you need to build a farm with a grain field and a windmill which will turn grain into flour. Flour will be then used in a bakery to produce bread. As you develop your city, you will unlock more buildings and more complex production chains.