You just need to connect your Twitter account to FeedBurner and a tweet would be sent out as soon as any new post became available in your feed.
Add Twitter Account To Socialize
- Go to your FeedBurner account at feedburner.google.com and choose any feed.
- Click on the Publicize option.
- Now, Click on Socialize from the left sidebar
- After complete the above steps, just click on Add a Twitter Account
- Authorize the app for your Twitter account.