You'll get the dialog very similar to next one.

Enter the name of project, select type of the Revision Control.
Press the 'OK' button.

Here you can enter the name of first target in this project - let it be test_ada. Select Type for this target to 'Ada executable'.
Press 'OK' button and you'll get your project window.


Press the OK button. If, you'll change the orientation of views (Ctrl-Alt-O), your project should looks like this:


All files should be placed in the Editor Window.
Now lets modify the source files as follows:
function Test_ada return integer is
begin
Put_Line("Hello from Gnat_test
!");
Ada_package.Hello;
Put_Line("Goodbye from Gnat_test
!");
return 1;
end Test_ada;
package body Ada_package is
procedure Hello is
begin
Put_Line("Hello
from Gnat_test !");
end Hello;
end Ada_package;
The entry point of this target is in the test_ada.adb file. This code is putting line "Hello from Gnat_test !", then call a procedure 'Hello' from package 'Ada_package', and puts the goodby text. The package 'Ada_package' consists from one procedure 'Hello' which is putting the greeting string.
The view of Ada source in Editor Window is shown at the next image. Note, that all code is indenting automatically, you are don't need to indent sources by hands.


If there are some errors in source files - in log window will be 'red' (errors) and/or 'cyan' (warning) lines: double click on them will popup corresponding source on error line.
Now double click on target - it will be executed, with the following output in project log:

Move cursor to new target and add the source file with the boby of new
target, using the 'Add source' button -
.
When this source is appear in the Dependency Tree, drag'n'drop it
to the Working Area. Type in it the following code:
function New_test return integer is
begin
Put_Line("Hello from New_test !");
Ada_package.Hello;
Put_Line("Goodbye from New_test !");
return 1;
end New_test;
There is call to procedure 'Hello' from package 'Ada_package' - for proper compiling of this example we need to add this package in dependency tree of new target. To do so - move cursor selection to the ada_package.adb in the Dependency Tree and holding Ctrl+Shift keys Drag'n'Drop it (using mouse button 2) to new target, like this:

The file icon of file ada_package.adb will be appear in dependency of new_test.
And now, lets make this target using Drag'n'Drop. To do it - move the icon of target from Dependency Tree to the 'Make drop site' as shown below:

To execute new target also double click on it.