@suman mukherjee​ :

Create a new repository on GitHub where you want to store your notebooks. Then use the below commands in the terminal after you install git.

git init
git add . -> this is to Add all the notebooks in your workspace to the Git repository
git commit -m "Initial commit" -> commit the changes
git remote add origin <repository URL> 
git push -u origin master -> This command pushes the changes to the master branch of the remote repository.