Follow these steps for uploading an extension into chrome web store.
Step 1 : Go to https://chrome.google.com/webstore/developer/dashboard and login
Step 2 : Go to dashboard and click on Add new Item and accept google t&c
Step 3 : Upload zip file of the extension
Step 4 : Fill the form in next page and publish the extension
For more information follow this link https://developer.chrome.com/webstore/publish