Step 1 - Run 'dream maker'. It's a program in your BYOND folder - you may also have a shortcut for it.

Step 2 - Hit File -> New Environment. Name your game and the initial source code file.

Step 3 - Write stuff in the source code file. Congratulations, you have code!

Step 4 - hit File -> New, and select 'icon file' from the dropdown box. Enter a name.

Step 5 - Hit the 'palette' button above the white box that appears where your code was.

Step 6 - Draw stuff using the drawing interface. Congratulations, you have icons!

If you have not read it yet, please read the DM Guide