Commits can be pushed to a remote repository using Magit Status buffer.
Ensure you are on the correct local branch
The current local branch is shown at the top of the Magit Status buffer.
b b displays a popup to select a different branch if you are not on the correct branch to pull changes into.
SPC g s to open Magit Status buffer
P to open the pull menu
u to pull from the upstream remote repository. If this is not currently set, then a prompt appears to select the default upstream.
Changing the local history with a commit amend, extend, reword, rebase or squash will prevent changes being pushed to a remote repository that has the original history unchanged.
Magit will show
Unpulled from and
Unpushed to sections when the local and remote histories are different.
The push menu has the
-f switch to force a push with a lease (the recommended force type).
Fix rather than Force
Pushing a new commit that fixes an issue is usually preferable than re-writing history and forcing a push when working on a shared repository.
Communicate clearly in advance and get agreement from other contributors if a force is the only option.