I'm somewhat of a newbie, so I don't know how difficult this problem may be. Anyhow, I have been building a character model and at one point I got dissatisfied with the upper proportions and decided to select the waist on up and delete it. I kept the lower part, because I was happy with it. However, now I got a big hole where the waist is and I would like to cap it so that I can smooth shift another torso, arms, head, etc. I tried selecting all the points in order and applying "make polygon", buy the edges are square and do not conform to the body. This is illustrated in the second snapshot. So, how can I cap this off, without having the squared edges?

Your expertise is appreciated,