Add a first steps document

ChangeLog

@@ -1,5 +1,6 @@
 2018-09-24  Markus Gans  <guru.mail@muenster.de>
 	* Stricter use of the keyword virtual
+	* Add a first steps document
 
 2018-09-20  Markus Gans  <guru.mail@muenster.de>
 	* Added pkg-config file finalcut.pc

doc/first-steps.md

@@ -0,0 +1,100 @@
+
+First steps with the Final Cut widget toolkit 
+=============================================
+
+
+How to use the library
+----------------------
+
+At the beginning of this introduction to the Final Cut usage, 
+we start with a little example.
+
+It creates an empty 30×10 character dialog.
+
+**File:** *dialog.cpp*
+```cpp
+#include <final/final.h>
+
+int main (int argc, char* argv[])
+{
+  finalcut::FApplication app(argc, argv);
+  finalcut::FDialog dialog(&app);
+  dialog.setText ("A dialog");
+  dialog.setGeometry (25, 5, 30, 10);
+  app.setMainWidget(&dialog);
+  dialog.show();
+  return app.exec();
+}
+```
+*(Note: Use mouse or <kbd>Shift</kbd>+<kbd>F10</kbd> or 
+<kbd>Ctrl</kbd>+<kbd>^</kbd> to close the dialog)*
+
+
+After entering the source code in *dialog.cpp* you can compile 
+the above program with gcc:
+```cpp
+g++ -O2 -lfinal dialog.cpp -o dialog
+```
+
+
+How it works
+------------
+
+
+```cpp
+#include <final/final.h>
+```
+All final cut programs must include the *final.h* header. 
+
+```cpp
+finalcut::FApplication app(argc, argv);
+```
+In this line creates the `finalcut::FApplication` object `app` with 
+the command line arguments `argc` and `argv`. This object manages 
+the application main event loop. It receives keyboard and mouse events 
+and sends them to the target widgets. Before widgets can be created, 
+an application object must be created! Only one `finalcut::FApplication` 
+object should be created.
+
+The next line
+```cpp
+finalcut::FDialog dialog(&app);
+```
+creates the `finalcut::FDialog` object `dialog` with the object `app` 
+as parent object. The `finalcut::FDialog` class is the base class for 
+creating dialog windows.
+
+```cpp
+dialog.setText ("A dialog");
+```
+The title bar of the dialog box gets the text "A dialog".
+
+```cpp
+dialog.setGeometry (25, 5, 30, 10);
+```
+The dialog window geometry is set to a width of 30 characters and
+a height of 10 characters. The window is positioned in the terminal 
+at the positions x=25 and y=5. (Note: x=1 and y=1 represents the upper 
+left corner )
+
+```cpp
+app.setMainWidget(&dialog);
+```
+The `dialog` object is selected as the main widget for the application. 
+When the user closes a main widget, the application exits. 
+
+```cpp
+dialog.show();
+```
+A window or widget is not visible directly after its creation.
+Only the call of `show()` makes it (and its child objects, 
+if available) visible.
+
+```cpp
+return app.exec();
+```
+The last line calls `exec()` to start the application and return 
+the result to the operating system. When the application starts, 
+it enters the main event loop. This loop doesn't end until the 
+window/application is closed.
+