you want to add some more changes to that last commit, you can simply stage them as normal and then commit again:
$ git add some/changed/file.ext
$ git commit --amend -m "commit message"
or you can Hard and Soft commands :
neither produces any new commits nor does it delete any old ones. It works by resetting your current HEAD branch to an older revision (also called "rolling back" to that older revision):
$ git reset --hard Commit ID
After this command, your currently checked out branch will be at revision commitID. The commits that came after this one are effectively undone and are no longer visible in the history of this branch.
Be careful, however: calling the command with the "--hard" option will discard all local changes that you might currently have. The project is completely restored as it was in that past revision.
If you call it with "--keep" instead of "--hard", all changes from rolled back revisions will be preserved as local changes in your working directory.