Hi Cassie,
In order to make a good job of the alteration, you'll need to carefully remove the ribbed trim (that's the bottom band of fabric at the hem). The goal here is to separate the seam not just cut it off. Then you'll need to decide just how much shorter you want your shirt to be. After you've answered that question, spread your shirt out flat on a table, ironing board etc. Then using a measuring tape or a ruler if you have a good flat surface to work on, measure how much you want to cut off from the bottom of your shirt. You're going to be sewing the rib trim back on the shirt , so you have leave yourself about 1/4 to 1/2 inch of fabric for the new seam at the bottom. For instance, say you want your shirt to be 2 inches shorter, you'll cut off only
1-1/2 to 1-3/4 inches from the bottom of your shirt.
OK, now you are ready to cut the extra fabric from the bottom of your shirt. Measure up from the hem
the amount you've decided you want to remove. Using a marking tool (can be anything that leaves a mark you can see on your fabric or use pins) make a mark every 2-3 inches all around the bottom of the shirt. Now follow your marks and cut the extra fabric off.
To sew the rib back on: First you need to make sure the rib is attached evenly all around the bottom of the shirt. Lay the shirt flat again. Now pick up the side seams and bring them together. This is the same as if you had folded your shirt in half from top to bottom. You now have measured the distance around your shirt into fourths. Make a mark at each fold. This will be a mark at the center front, the side, the center back, and the other side. Put your shirt aside and fold the rib trim into fourths the same way you folded your shirt. Mark the rib into fourths just as before. Now match the marks on the rib to the marks on the shirt.
Pin the rib to the shirt matching the marks on both pieces. The rib will be smaller than the hem. That's OK. Stretch the rib to fit. Now using a zig-zag stitch or stretch stitch on your sewing machine, sew around this new seam joining the rib to the bottom of your shirt. Sew this same seam twice for extra strength.
Now you're done! The actual process to do this repair can be a little daunting if sewing isn't your "deal". If that's the case, fabric stores usually have a list of people that make alterations or some dry cleaners can provide the same service.
Hope this helps
HomeQueen, June 2008