Not necessarily. There are illegal versions that use the orangish icon as well. The easiest way to tell is if you get a pop-up telling you how many days of the trial you have left. Then you have the legal version. I'm assuming you haven't paid for it because people generally know what they have paid for. If you don't get that box, it is an illegal version.
To actually answer your question, you can open up the script editor by pressing the icon on the toolbar (pencil and paper) or by pressing F11. You can edit existing scripts there or add a new one by right clicking a script on the bar on the left-hand side of the window and clicking insert. You can then copy and paste a script from the internet.