Once opened, the main Logical Modeler window will appear something like this:
You should also be familiar with 2.4.6 Performing Actions on Diagram Objects.
Notice that the name of the model and any abstraction selected is displayed in the main window title bar. (The phrase Entire Model Shown indicates that no abstractions are active).
To access the user guide for the Logical Modeler, use the Help menu (pressing the F1 key when the main window is shown will display the Visio help text). Pressing the F1 key when a logical modeler dialog is shown (e.g. Create Data Entity) will show help for that dialog.