我在主分支（提交）中添加了一个文件，当我想添加另一个文件时：它说
! [rejected] master -> master (non-fast-forward)
error: failed to push some refs to 'https://github.com/XXXX/helloWorld.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Merge the remote changes (e.g. 'git pull')
hint: before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
我真的有这个问题，我不知道它背后的逻辑。某人能否告诉我为什么我会看到这个问题以及我应该怎么做？
谢谢