create a new repo

1. initialization a repo

mkdir NEWDIR
cd NEWDIR
git init

2. make a connection with local repo and remote repo

git remote add origin https://github.com/doctorhui/Blog.git

3. make your change to local repo

echo "blablabla" >> README.md
git add README.md
git commit -m "first commit"

4. synchonize local repo and remote repo

git push -u origin master

5. make change in your local repo

git add
git commit -m "foofoo"

6. synchronize local repo and remote repo

git push 

push an exiting repo

all you need to do is the third step

reference

liaoxuefeng

ruanyifeng