After connecting to a Mongo server instance, you can open a contex menu by clicking the right mouse button on the server connection. There is the option "Add database". Clicking on it will open a pop up with the possibility to enter the name of the database. With a click on the button "Save" the pop up will be closed and the database created.
When creating a database is to be noted that the new name complies with the naming conventions of MongoDB and the database does not exist on the server.