PL/SQL :: Ora-00936 Missing Expression?

i am posting create and insert statements for a problem i am facing

create table tgh(NAME VARCHAR(20),LANG VARCHAR(20))

insert into tgh values('AC','ORIYA')
insert into tgh values('DF','BENGALI')
insert into tgh values('ik','english')

the below statements are for table copu

create table copu(CNAME VARCHAR(20),CLANG VARCHAR(20))

insert into copu values('ACdf','oriya')
insert into copu values('deg','ptot')

when i do  another insert as shown below

insert into copu (cname,clang) values  where
copu.cname not exists in( select  tgh.name,tgh.lang from tgh where upper(tgh.name)=upper(copu.cname))

i get ora-00936 missing expression