git commit : a new commit
git branch : a new branch
master * : means current ,use 'git checkout branchName' to switch or commit
git rebase : with git merge
git checkout :switch branch
git checkout name^: ^means its father
git checkout name~num: ~num means its father for num times
git branch -f master HEAD~2:means force master to head`s father twice

new repositories->import local repositories(grab the cammand like :'git remote add origin http://your repo.git' and 'git push -u origin' )
mkdir->git init
git add->git commit -m "xx"->git push origin master