Each model is saved in a separate file, with an extension specific to its model type. When you save a model, PowerDesigner also automatically creates a backup copy.
Select File > Save.
or
Click the Save tool in the PowerDesigner toolbar.
or
Right-click the model in the Browser and select Save.
Right-click the model and select Close.
Next Steps
Now that you are familiar with the PowerDesigner Interface, you will want to start experimenting with a particular type of model suitable to your needs.