1> write following commans for using as root
$ su
after that enter your pc login password
2> write following commans for changing the directory in the repo to where you want to work
$ cd
3> write following commans for creating new file in the repo..
$ nano .txt/.c
copy and paste the file here
use CNTRL+O to save the file and press ENTER and then CNTRL +X to exit
4>write following commans for adding the file
$ git add .txt/.c
5>5>write following commans for pulling previous works that have been done
$ git pull origin master
6> write following commans for pushing the file into repo
$ git push -u origin master
after that you need to enter
Username for 'https://github.com': Password for 'https://@github.com':
7> write following commans for committing the changes
$ git commit -m " comment for the file"