You can open different types of files in the *Workbench* by clicking
them in a view such as the Package Explorer view. For example, you
can click **Test.m**, the name of the file you created,
and it will be opened in a special *Mathematica* code editor in the
*Workbench*.

You can now type a definition of a *Mathematica* function
into the .m file. When you have done this and saved the file,
the name of the function appears in the Outline view;
in the image it appears in the lower left and has the title **Outline**.
The Outline view of *Mathematica* source code is a very
useful way to get an overview of all
the function definitions. If you click the name of
a function in the Outline view, the definition is displayed
in the editor.

If you click the notebook file, **Test.nb**, it will be opened
in the *Mathematica* notebook front end. This is a useful way to
enter temporary definitions, experimental features, and sample
cases while you develop *Mathematica* solutions.

If the notebook front end does not open, you should check
the location of the front end as specified in the Workbench
preferences.
From the menu bar, select **Window > Preferences**, and
then click **Mathematica**. Here you can set the location of
the notebook front end. More information is found
in the
preferences reference.

When you open a notebook from a project, *Mathematica*
is configured so that you can load and run code from the
project. For example, in the **Test** project you can
click the notebook file, **Test.nb**, then you can load
the .m file and execute commands.

When the *Workbench* runs in this mode it is not strongly connected
to *Mathematica*, so that if you modify your code you will have
to manually load it, and you cannot do debugging. For these, you need
to do a launch in run or debug mode.