Connection Name: MyConn
UserName:SomeUser
password:SomePassword
Connection Type: Basic
Role: default
Host Name: 12.12.12.12
port:2521
SID: xe

CREATE DATABASE LINK MyDBLink
  CONNECT TO SomeUser
  IDENTIFIED BY "SomePassword"
  USING '(DESCRIPTION=
  (ADDRESS=(PROTOCOL=TCP)(HOST=12.12.12.12)(PORT=2521))
  (CONNECT_DATA=(SID=xe)))';