how do you write the alter syntax for these table in sql?

create table mo_money (mac varchar2 (30), conteh varchar2(25), telephone_number number(10));

CREATE INDEX invoices_vendor_id_index ON invoices (vendor_id)

CREATE TABLE customers

( customer_id NUMBER NOT NULL, customer_first_name VARCHAR2(50) NOT NULL, customer_last_name VARCHAR2(50) NOT NULL, CONSTRAINT customers_pk PRIMARY KEY (customer_id) );

CREATE ROLE ar_user;

GRANT CREATE SESSION TO ar_user; GRANT CREATE PUBLIC SYNONYM TO ar_user; GRANT SELECT ON customers TO ar_user; GRANT INSERT ON customers TO ar_user;