Let me teach you how to sew a frock. In this image you can see a frock and a pant. The kid can wear the frock alone else the pant also.

This frock consists of two parts , the chest part and the umbrella shaped skirt attached to it. First draw the stitching pattern for all parts to get a clear idea. Now take the cloth to be stitched. Fold the cloth breadthwise then lengthwise , place the stitching pattern and mark the edges. Next cut along the corners like the image below.