Improovements like automatic closing of braces.

I have used this editor as well as sublime text. I found so many things needs to be implemented in code mirror compared to other text editors as sublime text provides rich functionality. I would like to contribute in this organisation. Please can anybody help me out how to start so that i can proceed by adding one by one features same as sublime text. I have enough experience of javascript to start with.

A good start would be to read the addons section of the manual, which will tell you that there is already an addon that autocloses braces.