Here's a quick article on how to sign up for Twitter.
Step 1. Go to https://twitter.com/
Step 2. On the right side of your screen click Sign Up.
Step 3: Add your information (Name, Password, etc). Then follow all the other prompts on creating a Twitter.
Step 4: After you have finished going through all of the Twitter prompts. Go into your Multibrain settings and Connect your new Twitter Account!