How do you return a select query in PL/SQL?

I want to create a stored procedure on ORACLE database server and my problem is that, I don't know how can I return a select statement .

Here is the logic, which should within the procedure:

Input paramters: filter1 (int), filter2 (string)

with cte as
(
    select  val1, val2, stddev(val3) from tab1 where parameter1 = filter1 and paramter = filter1 group by val 1, val2
)
 SELECT cte.*,
    round(some calculation) as final_results FROM cte

Afterwards I want to use this procedure in a MS asp.net application, with help of the MS ADO.net and MS Entity Framework 4.2.

Lot of thanks, for your response!