Added documentation for the "Download Content" form

Author: sweiland-openrails

Source/Documentation/Manual/images/download-content-form.png

@@ -16,7 +16,24 @@ installation profile.
 
 .. image:: images/start-activity.png
 
-If not, then you must download some content and add it as an Installation Profile.
+If not, then the next ``Download Content`` form is shown where you can download content. This form is described in the next `Content` chapter.
+
+Content
+=======
+
+Clicking on the ``Content`` button makes the ``Download Content`` form popup (if not already there for an new empty Open Rails installation):
+
+.. image:: images/download-content-form.png
+
+Select the route to be installed. This list will be enlarged by the OR team when suitable routes become available.
+However it is still possible to install routes manually as described in the next chapter.
+
+* ``Install path`` and ``Browse``: Fill in or Browse to the path where the route is to be installed. Each route will be installed in it's own subdirectory.
+* ``Info``: Gives more information of the selected route. The default web browser will be started with the information page.
+* ``Install``: Installs the selected route. A popup mentions the directory where the route is to be installed before starting the actual install. Installation profile gets added also.
+* ``Start``: Some routes have default start parameters and can be started via this button with these parameters.
+* ``Delete``: Delete route with this button. Take care: whole directory including added and changed files gets deleted.
+* ``Update``: GitHub based routes can get updated after the install by means of this button. Check for updates is done when clicking this button. Or at the end of the information webpage. Also GitHub has a watch possibility for getting changes on the repository being mailed.
 
 Installation Profiles
 =====================