It is very easy and manageable for anyone to do it regardless of whether you happen to be a professional or not.  For any questions, you can call for assistance. All you have to do is miter the crown molding corners to 45 degrees so that they will match up and then just install it with the adhesive. Installing the polyurethane molding will guarantee that there will not be any swelling, shrinking, warping, and bugs to not take a liking to the material so that it will always remain pest-free. If this is the first large home improvement project that you have started, don't worry, it is nothing to be wary about. One great tip though, definitely draw it our first so that you know exactly how and where everything is going.