Show me an simple example of Oracle Streams?
A pretty good resource is the blog: We Do Streams
A good starting point is: Oracle Streams One Way Table Replication 101
You have to do your research about what kind of Streams setup you want to make. For a downstream setup (this means that the capture of changes in the database you use as source, will be made in the destination system) you can follow this simple guide.
You can find details about each step of the setup at oracle's site.