Cannot write if or select above begin on a procedure - stored-procedures

Question

Im building a procedure for a class proyect where i have to invent some procedure related to my country football league. Right now im developing a procedure to show the results of a match, with the trainer, players, cards and goals after introducing the league round and a team. The thing is, i cant set the date of the round to a variable i created with an if due to a expected one of the following error on the if structure ( i have created just two rounds so that is the reason there are only two conditions), and i cant select data from tables into the other variables i have created for storing the data that doesnt need to be on the cursor due to being unique for each match, the referees names and the trainers names, but there is also another "expecting" error. Any help? Thank you in advance!
PS: The rest of the code is still on development so there could be some incomplete parts. Arbitro stands for referee, entrenador stands for trainer or manager, nombre stands for name and partido stands for match
Error:
create or replace PROCEDURE COMPROBARPARTIDO(JORNADA IN NUMBER, EQUIPO IN VARCHAR2) AS
FECHA DATE;
ELOCAL VARCHAR2(30);
EVISITANTE VARCHAR2(30);
ARBIP VARCHAR2(30);
ASISTENTE VARCHAR2(30);
IF JORNADA = 1 THEN
FECHA:=4-03-2021;
ELSIF JORNADA = 2 THEN
FECHA:=13-03-2021;
ELSE
DBMS_OUTPUT.PUT_LINE('ERROR');
END IF;
SELECT APR.NOMBRE INTO ARBIP, ASS.NOMBRE INTO ASISTENTE, ENL.NOMBRE INTO ELOCAL, ENV.NOMBRE INTO EVISITANTE
FROM PARTIDO_JUGADOR PA
INNER JOIN PARTIDO P
ON PA.ID_PARTIDO = P.ID
INNER JOIN EQUIPO EL
ON P.ID_LOCAL =EL.ID
INNER JOIN EQUIPO EV
ON P.ID_VISITANTE = EV.ID
INNER JOIN ENTRENADOR ENL
ON EL.ID_ENTRENADOR = ENL.ID
INNER JOIN ENTRENADOR ENV
ON EV.ID_ENTRENADOR = ENV.ID
INNER JOIN PARTIDO_ARBITRO PAR
ON P.ID = PAR.ID_PARTIDO
INNER JOIN ARBITRO APR
ON PAR.ID_ARBITROC = APR.ID
INNER JOIN ARBITRO ASS
ON PAR.ID_ARBITROA = ASS.ID
WHERE P.FECHA = FECHA AND (EQUIPO =EV.NOMBRE OR EQUIPO = EL.NOMBRE);
CURSOR C1 IS
SELECT J.NOMBRE, J.APELLIDO, EQ.NOMBRE
FROM PARTIDO P
INNER JOIN PARTIDO_JUGADOR PJ
ON P.ID = PARTIDO_JUGADOR.ID_PARTIDO
INNER JOIN JUGADOR J
ON PJ.ID_JUGADOR = J.ID
INNER JOIN EQUIPO EQ
ON J.ID_EQUIPO = EQ.ID
ORDER BY EQ.ID, J.COD_POSICION ;
BEGIN
NULL;
END COMPROBARPARTIDO;

Answer 1

About the structure I commented about:
create procedure as
<declaration section>
begin
<executable section>
end;
You put
executable statements (if) into declaration section, then
there's select that follows (invalid ... there should be only one into keyword), and
surprise! - a cursor declaration (?). BTW, you "declared" it and never used it
refer to dates as dates; either by using to_date with appropriate format mask, or use date literal (as I did)
Code that might compile (can't tell, don't have your tables); see if it helps.
CREATE OR replace PROCEDURE comprobarpartido(
jornada IN NUMBER,
equipo IN VARCHAR2
)
AS
fecha DATE;
elocal VARCHAR2(30);
evisitante VARCHAR2(30);
arbip VARCHAR2(30);
asistente VARCHAR2(30);
CURSOR c1 IS
SELECT j.nombre,
j.apellido,
eq.nombre
FROM partido p
INNER JOIN partido_jugador pj ON p.id = partido_jugador.id_partido
INNER JOIN jugador j ON pj.id_jugador = j.id
INNER JOIN equipo eq ON j.id_equipo = eq.id
ORDER BY eq.id,
j.cod_posicion;
BEGIN
IF jornada = 1 THEN
fecha := DATE '2021-03-04';
ELSIF jornada = 2 THEN
fecha := DATE '2021-03-13';
ELSE
dbms_output.put_line('ERROR');
END IF;
SELECT APR.NOMBRE, ASS.NOMBRE, ENL.NOMBRE, ENV.NOMBRE
INTO ARBIP , ASISTENTE , ELOCAL , EVISITANTE
FROM partido_jugador pa
INNER JOIN partido p ON pa.id_partido = p.id
INNER JOIN equipo el ON p.id_local = el.id
INNER JOIN equipo ev ON p.id_visitante = ev.id
INNER JOIN entrenador enl ON el.id_entrenador = enl.id
INNER JOIN entrenador env ON ev.id_entrenador = env.id
INNER JOIN partido_arbitro par ON p.id = par.id_partido
INNER JOIN arbitro apr ON par.id_arbitroc = apr.id
INNER JOIN arbitro ass ON par.id_arbitroa = ass.id
WHERE p.fecha = fecha
AND ( equipo = ev.nombre
OR equipo = el.nombre
);
END comprobarpartido;

Answer 2

To set declaration values according to conditions, you can use case. For example:
fecha date :=
case jornada
when 1 then date '2021-03-04'
when 2 then date '2021-03-13'
end;