SQL & PL/SQL

The following trigger:

create or replace trigger my_trigger
before update on employees
for each row
begin
insert into kperumal values(first_name);
end my_trigger;

is giving the following error:

ERROR at line 2: PL/SQL: SQL Statement ignored

1. create or replace trigger my_trigger
2. before update on employees <- This is where error is coming.
3. for each row
4. begin

Can someone help me?