Drush How to sync between local and server? I always deploy drupal locally, install need modules, and then write the theme. Then I upload the local site to my server.

But when something needs a update or change, I will modify the local site, and I re-upload the local site to server.

It's very troublesome.

I want to: 


  sync my local site to my production site, so that when my local site is changed, the updates are uploaded to the server automatically.


It seems that Drush can sync between local and server, and might be useful for this issue, but I can't find useful post explaining how to do this. 

Thanks
what your looking to learn to do is called drush aliases.

You can read this: https://drupal.org/node/670460

And here are some examples of it: http://deeson-online.co.uk/labs/drupal-drush-aliases-and-how-use-them

I would suggest you to use a virtualbox installation of drupal to test this out so you can get familiar with it first by setting this up: https://drupal.org/project/quickstart

My main local environment for developing drupal sites resides in the virtualbox quickstart. From there I do my tests and you can sync to your live environments using drush aliases. You can test syncing just using the local sites first.