Due to recent changes the the twitter interface, it is now slightly harder to configure a feed on your website.
Here is how to do it :-
From your site dashboard select Twitter Widget Settings :

Now goto you twitter account Apps https://dev.twitter.com/apps and click create a new application

Fill the following page and create the App – (Name may need to be different to make it unique).

Click on Create my Access Token.
Now Copy and paste the fields back into the Twitter Widget Settings page on your website.
OAuth Consumer Key: Consumer key
OAuth Consumer Secret : Consumer secret
OAuth Access Token : Access token
Access token secret : Access token secret
Then Click Save.
That’s it your twitter feed will now work.