Serge or zig-zag around all the pieces
Use a long stitch without backstitching at beginning or end.
Pull on the thread to gather the fabric then adjust gather to match the width of polka dot piece
Do the same with the back piece
With right sides together, sew down side seams. Press seams open and sew hem. (later I decided I wanted more length so I added a contrasting strip of the polka dot fabric)
and little pleated pockets with a purely decorative FIMO clay button