In order to implement twitter oAuth in your application you need twitter consumer key and consumer secret which are used to make twitter API calls. So register a new twitter application and get the keys
1. Go to https://dev.twitter.com/apps/new and register a new application. Fill application name, description and website
2. Give some dummy URL in the callback URL field to make the app as browser app. (If you leave it as blank it will act as Desktop app which won’t work in mobile device)
3. Under the settings, tab upload icon and change the access type to Read and Write.
4. Copy Consumer Key & Consumer Secret key
You did. Now you can start using Twitter API in your project using copied secret keys.
Last step is to specify consumer(API) key and consumer(API) secret in the plugin setting. As an option you can also do this using coding, but is much easier to use GUI.
Open Windows → Mobile Social Plugin → Edit Settings
And fill in Consumer key and secret.
All done, now you can use Twitter API.