how can i create glass material

In order to make glass it is best practice to use multiple layers. So you have a transparent material for the outside but also for the inside. Please make sure that the inside mesh also has reversed normals to create the illusion of having ” layers”  of glass as you see in real life. After having an inside and outside layer you can also try to have more duplicates of those layers with different transparent materials to add more depth or highlights. Also make sure each layer of glass has its own unique material in order to prevent render order issues.
I hope this information helps you to create a glass material.