How to create stored procedure in oracle

CREATE OR REPLACE PROCEDURE sp_Print As Begin DBMS_OUTPUT.PUT_LINE('Hello World'); End; EXECUTE sp_Print; --------------------------------------------------------------------------- CREATE OR REPLACE PROCEDURE SP_ADDTWONUMBERS ( NUM1 IN NUMBER, NUM2 IN NUMBER, NUM3 OUT NUMBER ) AS BEGIN NUM3 := (NUM1 + NUM2); DBMS_OUTPUT.PUT_LINE(NUM3); END; VAR NUM3 NUMBER; EXEC SP_ADDTWONUMBERS (12,10, :NUM3); PRINT NUM3