u/Thread-Spinner-7887

I’m currently studying fashion and my assignment is to drape a shirt and we’re not allowed to hand sew, it has to be all done on machine. I’ve draped this spine-like thing here but I have absolutely no clue how to sew that on the machine without visible stitching, is it possible? My teacher reckons it is and says that I will “figure it out” and I just need to experiment with it which is really giving me no where to start with it 😅

My grandma wants me to shorten the hem of this top for her and I want to make it look like the old hem which has this stitch on it. I’m not sure what it’s called though - it looks like an overlock stitch but only on the one side. I have a Singer SC220 and my manual says it has an overlock stitch which is what i assume would be the closest thing to it but i can’t for the life of me find that stitch on my actual machine. Any advice is greatly appreciated