I started doing step by step instructions for you all but it got a bit messy through the process.
Took the sides in about five inches on both sides
Chopped the bottom off right above the knees so there was would be plenty of fabric to play with for the sleeves.
Measured the sleeves, sewed them together and put elastic at the end.
Sewed the sleeves into the arm holes -
Here is a close up of the sleeve - I love the poof!
Before & After!