Create a database = DONE
Connect to the database = DONE
Read about a migration in Yii2 = DONE
If possible create a migration = DONE
Create users table migration
Create posts table migration
Implement a Database user login system
Show the posts link to authenticated users only
Read about database seeding
Do ajax submit for comments and likes and replies
Read about Yii2 user RBAC
Try to implement in your project