C:\>sqlplus mike/lion@ora8

SQL> create database link dbl_ora10
  2  connect to scott
  3  identified by tiger
  4  using 'ora10';

Database link created.

SQL> -- check whether DB link works properly
SQL> select 'x' from dual@dbl_ora10;

'
-
x

SQL> -- testing environment: one table per user
SQL> create table my_first_tab (col number);

Table created.

SQL> -- a "remote" table
SQL> connect scott/tiger@ora10
Connected.
SQL> create table my_second_tab (col number);

Table created.

SQL> -- returning back to create a trigger
SQL> connect mike/lion@ora8
Connected.
SQL> create or replace trigger trg_my_1_tab
  2  after insert on my_first_tab
  3  for each row
  4  begin
  5    insert into my_second_tab@dbl_ora10 (col) values (:new.col);
  6  end;
  7  /

Trigger created.

SQL> -- OK, let's insert a record into a "home" table.
SQL> -- Trigger should insert it into the remote table.
SQL> insert into my_first_tab values (1234);

1 row created.

SQL> -- home
SQL> select * from my_first_tab;

       COL
----------
      1234

SQL> -- remote
SQL> select * From my_second_tab@dbl_ora10;

       COL
----------
      1234

SQL>