Heaven help me!

I have a to sew a costume today. The 3 little kiddos are doing a Wizard of Oz theme for Halloween tomorrow. Avery is going to be Dorothy, Zane the lion, and Cole is going to be the tin-man. Avery and Zane's costumes were store bought and adorable. That leaves me with Cole's costume. Me, being the procrastinator I am bought the material a few weeks ago but it has sat in the bag ever since. Oh, and there's only one other teensy tiny detail...I don't sew. Ok, that might not be entirely true, but I don't have the slightest idea on how to read a pattern. So I'm just going to free-hand it, and hope for the best. I have it all planned out in my mind, let's just hope I can convert my vision to fabric and thread.