UML diagrams use different types of arrows. Each arrow type represents another relationship. Sometimes the relationships are depicted in the same way, but they have a slightly different meaning. In that case, they can be annotated with a stereotype.
Each connector tool has defined a default direction in which it is inserted into the diagram. You may change this setting using the context menu for the tool.
You may place a new element on a relationship. It will cause splitting the relationship into two parts which will be connected to the original start and end element on one side and to the new element on the other side.