Hi @sahar78, thank you for participating in this contest!

Unless it is a scientific anatomical study, these measurements are unnecessary, without considering that these measurements are completely arbitrary, without a real basis.
It is much better to educate the eye, learning to establish relationships between the different parts of the model that we want to draw.
Ignoring that detail, your drawing of the hand in the attitude of using a lighter seems fine to me. There are some details that could be worked on to achieve more intensity in the attitude but in general, it is very good. I like the lines in your drawing, they denote security.