I am new user of the Bracket text editor. Can anyone tell me how to integrate SASS extension and how to use it?
You need to start by reading the samples on the current github project as a beginner reference to making your own: Bracket Sass
After that, you should get the idea: in the base root of your folder you need to include a .brackets.json file, dot at the beginning in order to make it invisible to your system. In this file, you will write in your own way (or by following the read me I linked you to) the Sass compilation parameters for your Brackets project. Therefore, keep in mind your project structure, your assets and dependencies for Sass.
This should be only your initial setup, restart Brackets for double measure and see what happens.