1) The document provides guidance for teachers on how to sign up for and effectively use Twitter for professional learning and collaboration. It explains how to find people to follow through your email contacts and relevant organizations, and how to search Twitter to find more people based on subject area or hashtag topics. 2) Key Twitter features covered include the timeline, profile stats, trends, expanding tweets, retweeting, mentioning others, searching, and using hashtags to organize conversations. Shortened URLs and the 140 character limit are also addressed. 3) Teachers are encouraged to join conversations by contributing their thoughts, sharing websites, and using hashtags and retweets to find audiences and spread information concisely.