Much of your interaction with the simulation will be through the objects in the simulation tree that was added to the Explorer pane.
The tree represents all the objects in the simulation. At this point the tree is rather sparse, but nodes will be added in later sections when a mesh is imported and models are defined in the continuum. Most of your interaction with the simulation will be by selecting objects in the tree and:
The handle next to a node indicates that sub-nodes, or children, exist below that one. Click on the handle to open a node and show the children. Do the same for an open node to close it.
Most objects in the tree have one or more properties that define the object. Access to the properties is via the table in the Properties window.
To modify the properties of an object, click once on its node to select it. Depending on the type of property you may be able to edit it directly in the value cell. Otherwise, if there is an ellipsis button to the right of the value, clicking on it will display a property-specific dialog that may be more intuitive and guide you in setting values of complex properties.