my computer won't let me rotate these pictures :(
I started by cutting off the sleeves leaving a little around the seams so I could hem the edge.
I turned it inside out, put it on, and pinned the armpit where it would fit me. Then I took it off, pinned down the side at an angle to the bottom hem of the shirt, and cut off the excess.
Next, I pinned and sewed down the raw edges all around.
That's it. It's cute and comfy.