Step one is to make your pattern. I used a dress that fits the babes perfectly and is a similar fabric to what I wanted to use and got my bodice pattern from that.
Because I wanted a drop waist style dress I extended the bodice in an A-line to the length that I wanted it to hit her at. and I cut the back piece so that it was a able to line up with under the armpits (plus an inch or 2 for hemming). Cut 2 bodice pieces and 1 back piece.
Get your picture ready for the front. I used felt to do the cupcake and #1. I sewed ribbon strips to the cupcake top and then did french knots (so it look like it had sprinkles)
Stitch on the birthday fun-ness! I did a heart button - to look kinda like a cherry on top... I think it's cute.
after that has been stitched on place your straps down on the front piece (like pic)
then place your 2nd bodice piece over it and pin. and stitch from arm hole to arm hole.
Now take your back piece and double fold your hem and then shir I did 8 rows VERY close together. steam the shir so it gathers up a bit more.
pin your back and front together (I did french seams, so wrong sides together, stitch, turn and then stitch right sides together. )
For the bottom ruffle I used eyelet, double the length (ish) of the bottom of the dress. Gather it till it fits to the bottom of the dress.
pin it inside the dress - Right sides together and sew it on.
and you are done! One first (or whatever birthday number you chose to do) birthday dress!