Once Gaphor is started a new empty model is automatically created. The main diagram is already open in the Diagram section.
Select an element you want to place (e.g. a class) by clicking on the icon in the Toolbox and click on the diagram. This will place a new Class item instance on the diagram and add a new Class to the model (it shows up in the Navigation. The selected tool will reset itself to the Pointer tool after the element is placed on the diagram.
It's simple to add elements to a diagram.
Some elements are not directly visible. The section in the toolbox is collapsed and needs to be clicked first to reveal its contents.
Gaphor does not make any assumptions about which elements should be placed on a diagram. A diagram is a diagram. UML defines all different kinds of diagrams, such as Class diagrams, Component diagrams, Action diagrams, Sequence diagrams. But Gaphor does not place any restrictions.
Creating New Diagrams
To create a new diagram, use the Navigation section. Select an element that can contain a diagram (a Package or Profile) and right-click. Select New diagram and a new diagram is created. As of Gaphor 1.1.0 a buttion is available in the header bar. Select a package and you'll notice the button is not grayed out and can be clicked, resulting in a new diagram being added to the model.
Copy and Paste
Items in a diagram can be copied and pasted (in the same diagram or another). A paste will create new items in the diagrams, the items they represent (e.g. the Class that's shown in the Navigation) is not copied (call it a shallow copy if you like).
This way you can easely create visual copies of the same (underlaying) model element.
Drag and Drop
Adding an existing element to a diagram is simple: drag the element from the Navigation section onto a diagram. Not all elements that show up in the Navigation can be added: Diagrams and attribute/operations of a Class can not be added.
Elements can also be dragged within the Navigation section. This way classes and packages can be rearranged for example.
Note: this is a more advanced topic!
The UML method to extend UML (basic) components with a special meaning
is by using stereotypes. A stereotype defines a special usage of a model
element. For example: a class that's used as a controller can be
assigned a stereotype "controller". Stereotypes are always enclosed
Creating a stereotype starts by the creation of a Profile normally. Although stereotypes can be created in every package, it's a good habit to use Profiles for that. Next a Metaclass has to be created. The metaclass will tell the stereotype on which kind of elements it is applicable. A Stereotype can be connected to the Metaclass by means of an Extension relationship.
Stereotypes can be applied to basically all elements in a model.
Stereotypes can contain attributes, as shown in the diagram above. Those attributes can be filled in the Element Editor. This allows for enormous flexibility. In most cases, especially if some sort of program logic has to be generated from the models, it is very handy to define special behaviours to classes and other elements by means of stereotypes.