SQL & PL/SQL :: Create Table Constraints / ORA-00907

i am a beginner in SQL and want to create a table with the following constraints :

'orderno' should be primary key and start with o
'clientno' should be foreign key
'ordr date' is not null
'salesmanno' foreign key
'delytype' default value 'f' and possible value ( f or p)
'delydate' cannot be less than order date
'orderstatus' values ('in process.......)

here's my

create table sales_order(orderno varchar2(6) like 'o%' primary key,
clientno varchar2(6) foreign key references client_master(clientno),deldate date not null,dellyaddr varchar2(25),salesmanno varchar2(6) foreign key references salesman_master(salesmanno), delytype char(1) default 'f',billyn char(1),delydate date check > orderdate,orderstatus varchar2(10)check ('in process','fullfilled','cancelled');