If you get stuck on how to close the self lined straps, I hope this will help clarify the process. It's easy don't worry.
Once you have stitched the armholes and necklines - turned and presssed them - and stitched shoulder seams of the lining and dress together you are ready to close up the straps. This may seem like a puzzle at first.
1. First, with the dress right side out, reach inside the strap and pull out the
first side to close - right sides together and stitch closed.
2. Now, from the bottom of the dress reach
inside the dress/top, between the lining and the exterior
dress fabric. Grab onto strap from the inside and pull outside. The dress
will now be inside out.
3. Stitch the second side closed (inside you will see the other side of the
closed strap) and turn to the right side and press. That's it!