Twitter release their API version 1.1, you may need API key to use twitter related wordpress plugins, here is described shortly how you can get you twitter API key things.
1. First login to you twitter account
2. Go to https://dev.twitter.com/apps
3. Click on Create New Application button.
4. Fill up the form and submit it.
5. After submitting the form, Scroll down a little, you will see Consumer Key and Consumer Secret information, but you will still need access token.
6. Click “Create my access token” button at the bottom of the page, then you will get Access Token and Access Token Secret information. thats everything that you need!