i want to design a database for the social movements networks like twitter.
i want to know: what table(with field) i should create?
table that i create:
1. post
post_id, post_text, created_at, user_id, screen_name, name, profile_image_url
2. users
user_id, screen_name, name, profile_image_url, location, url, description, created_at, followers_count, friend_count, time_zone, last_update
3. post_tags
post_id, tag
4. comment
id, post_id, name, content, approved, date, parent, user_id

my database is mysql. what table or field should i add or change to my database?

great thanks...