as we can see from your log it seems that you have tried to create a database with Webmatrix and the user you specified didn't have the permission to create a database.
The database 'Coolschool' could not be created. ---> System.Data.SqlClient.SqlException: Login failed for user 'tanvir'.
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
Creating empty database for MonoX is required only when you are installing via MonoX Web installer. When you try to install MonoX with Webmatrix or WPI then they try to create a database for you and therefor the sql user needs to have the proper permissions.
Can you please check that permissions for the specified user and get back to us with the result ?