In the resources section, you have the ability to paint trees, stone, iron and pitch onto your map. There are two different types of forests, Coniferous and Deciduous. A visual representation is shown below:
In the other sub menus you can place the other resources. Using the 'Tile brush size' tool which remains consistent on all submenus, you can change the amount of resources you are adding to the map.
In the other three sub-sections from resources, there is also three radio buttons per page - one is called "Tile painting" and this is for actually painting the resources on your map. Another point is called "Decoration". This allows you to place actual stones for the stones, iron stones for the iron, and for pitch, you can place trees that belong in marshland.
The other option is entitled "viewing". This option removes anything that the user has ready to place, and allows you to just view the map and things that have already been placed.
In Stronghold Crusader 2, you can place the following Trees: