You don't. You just deploy to production (just like you did to the sandox). Just put in account username/password (vs sandbox username/password) and deploy to different endpoint (I believe it is https://www.salesforce.com/services/Soap/u/12.0 -- it's been a while since I've done it).
(Stupid salesforce and there Link escaping stuff) ... try again : https: //www.salesforce.com/services/Soap/u/12.0 (obviously no space between protocol and url)
After making your changes in Sandbox, you can use the Apex Deployment Tool to extract your configuration changes into files and deploy them to your production organization.
You can download a zip archive containing the tool and documentation from Setup > App Setup > Develop > Tools.
You can download a zip archive containing the tool and documentation from Setup > App Setup > Develop > Tools.