有一个示例，说明如何在其存储库上创建/添加和提交，可以帮助您修改文件。

https://github.com/nodegit/nodegit/blob/master/examples/add-and-
commit.js

关于提交和推送，这是我的代码的摘要，希望对您有所帮助。我花了相当长的时间才弄清楚这一点，感谢Gitter上的家伙，我终于找到了答案。

代码如下：

var path = require('path');

var nodegit = require('nodegit'),
    repoFolder = path.resolve(__dirname, 'repos/test/.git'),
    fileToStage = 'README.md';

var repo, index, oid, remote;

nodegit.Repository.open(repoFolder)
  .then(function(repoResult) {
    repo = repoResult;
    return repoResult.openIndex();
  })
  .then(function(indexResult) {
    index  = indexResult;

    // this file is in the root of the directory and doesn't need a full path
    index.addByPath(fileToStage);

    // this will write files to the index
    index.write();

    return index.writeTree();
  })
  .then(function(oidResult) {
    oid = oidResult;

    return nodegit.Reference.nameToId(repo, 'HEAD');
  })
  .then(function(head) {
    return repo.getCommit(head);
  })
  .then(function(parent) {
    author = nodegit.Signature.now('Author Name', 'author@email.com');
    committer = nodegit.Signature.now('Commiter Name', 'commiter@email.com');

    return repo.createCommit('HEAD', author, committer, 'Added the Readme file for theme builder', oid, [parent]);
  })
  .then(function(commitId) {
    return console.log('New Commit: ', commitId);
  })

  /// PUSH
  .then(function() {
    return repo.getRemote('origin');
  })
  .then(function(remoteResult) {
    console.log('remote Loaded');
    remote = remoteResult;
    remote.setCallbacks({
      credentials: function(url, userName) {
        return nodegit.Cred.sshKeyFromAgent(userName);
      }
    });
    console.log('remote Configured');

    return remote.connect(nodegit.Enums.DIRECTION.PUSH);
  })
  .then(function() {
    console.log('remote Connected?', remote.connected())

    return remote.push(
      ['refs/heads/master:refs/heads/master'],
      null,
      repo.defaultSignature(),
      'Push to master'
    )
  })
  .then(function() {
    console.log('remote Pushed!')
  })
  .catch(function(reason) {
    console.log(reason);
  })

希望这可以帮助。