github usage

Create a new repository on the command line
touch README.md
git init
git add README.md
# add all files in current direcory
git add .
git commit -m "first commit"
git remote add origin https://github.com/lingceng/HelloWorld.git
git push -u origin master

Push an existing repository from the command line
git remote add origin https://github.com/lingceng/HelloWorld.git
git push -u origin master