This dress is made by working 6 granny squares, joined together with shoulder straps created with trebles, then a series of trebles in rounds, with coloured treble rounds and puff stitch border to finish hem, and coloured double, treble and half treble rounds to create a ruffled cap sleeve.
The instructions and yarn quantities are written for DK yarn, but you could use 4ply with a 3mm hook if you wish, and continue to work additional rounds for the squares until they reach the given size. A 4ply garment will be much lighter weight than DK.