To create a procedure with a parameter and pass its value that way.
For example,
create or replace procedure p_disp(par_param in varchar2) is
begin
dbms_output.put_line(par_param);
end;
/
begin
p_disp('lf');
end;
/
If you meant to use that parameter in SQL, such as
select * From v$session where sid = :sid;
OR
select * From v$session where sid = &sid;
none of these works; you'd get ORA-01008: not all variables bound error.