Select the image you want to convert to CreatiSign code (or drag it onto the file selector) - all of the work will be done by your browser and there isn't so much room in Arc Signs, so use a very small image (32x32 max). Even in that case, if the image has many color variations, you may end up hitting the Arc Sign character limit. The image will NOT be sent to any server. You can save this page on your desktop and use it offline too, if you're concerned about that :)
Once you see text appearing down here in the textarea, select all of it, copy it and paste it in your Arc Sign, then tweak it as you please. A character count will also appear down here when the work is done.