Your blue shape is actually four different shapes. You can Group them and then Fill the group to add solid color to the whole shape.

In Excel there is no concept of "cells within the shape". Shapes exist in a conceptual layer on top of cells. You can determine the location of a shape relative to a cell, but there is no built-in concept of what cells are within the boundaries of the shape.

Last, I don't understand what this means: "i want to place formula within the Blue Shape"