There are 2 types of
User Twitter - The user logs in and sends the photo to their own account
Client Twitter - All photos go to a predefined Twitter account in the background without the user having to log in
Check this to allow users to log in to the own Twitter accounts to upload.
Check this and Login to a Twitter account that all photos will be uploaded to.
3. Current Account
This is the current logged in Twitter account for Client Twitter
Enter the message that will accompany the photo.
Note: Twitter allows 140 characters, but 25 of them are reserved for the link to the uploaded photo