how to make push work without deleting exitiing file

[Ouakala_Abdelaaziz]

Hello Sir,

i have problem with push command , when i try to push a file to bitbucket

it's give me an error

$ git push origin master
To https://bitbucket.org/O-Abdelaaziz/testcmd.git
 ! [rejected]        master -> master (non-fast-forward)
error: failed to push some refs to 'https://O-Abdelaaziz@bitbucket.org/O-Abdelaaziz/testcmd.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Integrate the remote changes (e.g.
hint: 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

the repositrory have just the md file , when i try to force push using this command

$ git push origin master -force

it's work but the md file it deleted , so im doing right here ? or what?

i want to push without deleting any thing.

can you help me.