You may notice that I ended up changing the neck and sleeve treatment from the earlier photos. This was because I had indeed not followed the directions properly and also I had a big problem with my shirring elastic which shredded. I don't know if this was because it was poor quality or if I zig zagged too close to the elastic, but I decided make a casing for some narrow elastic instead which solved both problems and didn't interfere with the overall look of the top.
Here is how you are supposed to do the neckline in case it's confusing (it's easy if you actually read the full instructions, unlike me!) The instructions tell you to neaten the neck and sleeve edges with closely spaced zig zag stitching and refers you to style 123. I skipped flipping to style 123 (it annoys me when they do that to save 2 lines of type) and just neatened the raw edges with my serger, applied the shirring elastic on the indicated lines and then realised that turning the seam allowance created a wavy mess. If you go to style 123 it says you should neaten the raw edges with closely spaced zigzag, then turn the seam allowance and zig zag again close to the fold then trim which presumably cuts off the neat edge you just made. ?? Then you would also have your two rows of zigzag stitching to attach the shirring elastic. I would experiment with your fabric and see what finish you prefer, like I did here;
Other than that I made no changes, except sizewise I found for me that the given finished width of the neck was too big and the sleeves to small so definitely check the fit before you finish the elastic.
Next I am going to make a simple skirt to coordinate (I know, astonishing for me isn't it!) with this top in this borderprint sheer fabric.