What happens next?

How to alter a shirt
Lay the well-fitting shirt over the ill-fitting shirt.
Lay your ill-fitting t-shirt out flat and then lay the well-fitting shirt over it. Make sure that both shirts are flat and lined up at the shoulders and neckline.

Pick from:
a). Leave the t-shirt sleeves on both shirts untucked. Trace along the edges of the well-fitting shirt.
b). Then, lay the ill-fitting shirt over the top and roll the material up to make a tight, rolling roll. Make sure to flatten your bumps as you roll your shirt.
c). Check the hem of the well-fitting shirt and hem of the ill-fitting shirt. If the bottom edge of the middle part of the shirt is hidden by the material, then you may want to layer the shirt to duplicate or correct this problem.
d). The shirt should be up to your neck when laying it on top of the ill-fitting shirt. Put a pencil mark on the backside of the shirt.
a).