how to create an explain plan for the below query? I'm getting ORA-00900: invalid SQL statement error
A CREATE VIEW statement has no execution plan as the SELECT will not be evaluated when you create the view. You need to first create the view, then run EXPLAIN on a query using the view:

create or replace view TaskView 
as
select T1.PersonID,T2.ID ,T2.Task 
from Table1 T1,Table2 T2
where T1.TaskID=T2.ID;


Then 

explain plan 
  set statement_id = 'TASK'
select *
from taskview;


or simply explain the underlying query:

explain plan 
  set statement_id = 'TASK'
select T1.PersonID,T2.ID ,T2.Task 
from Table1 T1,Table2 T2
where T1.TaskID=T2.ID;