The easiest way is to just run your world and click "Take Picture" when you get to the scene you want (set the world "seldom used property" speed multiplier to something less than one to make picking the exact time for the picture easier to set). You can also specifically set up a scene without animation, then run the world - a bit more work but also more control.
Edit>Preferences>Screen Grab gives you some options for the captured image. I would recommend just capturing a wide view of the scene you want and then cropping, editing etc. in another program like Paint or preferably Photoshop or Paint Shop Pro. That's much easier than trying to get everything right beforehand in Alice.