How to log in the Oracle APEX Application with Authentication 'Custom' type

I will emphasize a few points in the application:
1)Account Register
2)Sign in
3)Forgot Password

/*Table and Column*/
Table : MTL_USER:
Column: User_id(pk)
email
password,
verification_code
role_id

/*Function or Procedure*/
/*log in the application. if true then pass, otherwise false*/
function custom_authenticate
(
p_username in varchar2,
p_password in varchar2
)
return boolean;

/*register the account*/
procedure create_account(
p_email in varchar2,
p_password in varchar2);

/*Check the verification code*/
function verify_reset_password(
p_id in number,
p_verification_code in varchar2)
return number;

/*request the mail and send the email*/
procedure request_reset_password(
p_email in varchar2) ;

/*send the emai*/
procedure mail_reset_password(
p_email in varchar2,
p_url in varchar2) ;

/*reset password*/
procedure reset_password(
p_id in number,
p_password in varchar2) ;

/*check if the user is administrator*/
function authz_administrator(
p_username in varchar2)
return boolean ;

/*check if the user existed*/
function authz_user(
p_username in varchar2)
return boolean ;