I added a new Tutorial titled Using Openings for Exterior Details. If there are other subjects that you would like to see tutorials for please let me know.
Bill is the owner and maintainer of SoftPlanTuts.com
A simpler way to do that and which also solves the problem of seeing the opening from the inside (and also makes it display correctly in plan view) is to simply draw whatever opening shape you want -openings from the "arch" openings menu will give you most shapes.
And then draw in another piece of wall inside the opening.