Open the windows explorer and go to the Autoit3 program
subdirectory examples, C:\Program Files\AutoIt3\Examples\English, and
open msgbox.au3 by double clicking on it, or right mouse
click and select Edit. SciTE will open and show you
the script. As you can see, all different word types have their own
color for better readability. Now if you want to run this script, just
press F5.The script will start and show a
messagebox.

To start a new script, go to your Windows Explorer and do a Right mouse click/New/AutoIt v3 Script and
give it the name you want.
Now double click this new file and SciTE will open:

Let’s make the below program:
|
; This is my first
script |
You will see that when you type the editor will suggest
keywords or functions. you can either select one or just keep on typing.
In this example you type Ms
and hit Enter
or Tab
to select MsgBox
|
|
|
|
Then type ( and
a tooltip will be shown which assists you with the parameters: |
|
|
Now just type the rest: 0,
"My First Script!", "Hello World!")
|
When AutoIt3 detects errors in your script, it will show the Error in the Output Plane of the SciTE editor and you just double-click the red error line in the output window and SciTE will jump to the line in the code that contains the error:

Ctrl+F5 will run Tylo's AutoIt3 Syntax Checker, which will syntax check the whole script or
F5 will run Tylo's Au3Check and when no errors/warnings found run AutoIt3.exe.
Again just double click on the error and SciTE will jump to the line containing the error.

You can create an executable (.exe) of your script by hitting F7 or Alt+F7 for Beta. SciTE
will run the AUT2EXE program for you to create the program.
You can also Hit Ctrl+F7
to "Compile
your script with options" and change compile
options like the compression or Program Icon, but also the program
resource information like Programversion, Legalcopyright and additional
fields. see here for
more info.