This question already has an answer here:
Updates were rejected because the tip of your current branch is behind hint: its remote counterpart. Integrate the remote changes.
I was trying to push local octopress blog to remote branch. But its saying above error.
another is: Do i have to manage or push the local changes to source or origin branch.?
When i do username.github.io ,i shall see my remote version of the local blog.(i used rake deploy command) But i dont see the updated blog at my username.github.io.I have doubt on branch for origin and source.
You need to merge the remote branch into your current branch by running git pull.
If your local branch is already up-to-date, you may also need to run git pull --rebase.
A quick google search also turned up this same question asked by another SO user: Cannot push to GitHub - keeps saying need merge. More details there.
来源：https://stackoverflow.com/questions/25237959/updates-were-rejected-because-the-tip-of-your-current-branch-is-behind-hint-its