Here's how to move your drafted content:

1. Open your sandbox in Edit mode. (References and other templates will break if you copy from Read mode.)
2. Select the portion you want to move into the live article in mainspace.
3. Open the original article in Edit mode and add your content into the article.
4. Add an edit summary that says it copied from your sandbox, and click 'Publish changes'. (Include a link to your sandbox by typing [[User:Your Username/sandbox]] in the edit summary.)
5. Repeat this process for any other parts of the article you worked on.
6. Make sure that the lead section reflects the new content you've added. And copy-edit the article to ensure that your additions mesh well with the older content.

Once you've gotten the hang of it you can make further edits directly in the article, or repeat the sandbox procedure one portion at a time.