What, specifically, did you read? I can point you to the Oracle documentation, which is pretty thorough. But if that's what you're complaining about, that's not particularly useful.
The correct setup is going to be highly dependent on exactly what you want to do. Some systems require relatively complex setups. Others require relatively simple ones.
Regardless of what you implement, you'd obviously want to test in a lower environment before implementing in prod so you know how your prod environment will actually behave.
As I asked before, what did you read that was "very complicated"?
The top result from a search for "Oracle Resource Manager" was this white paper on Managing Oracle Resource Manager. That walks through a relatively simple example. The Resource Manager chapter of the Database Administrator's Guide is also pretty good.
If you have specific problems understanding some particular step from one of these docs, we'd be happy to help. Of course, we're getting a bit off-topic for a Security forum. If you have specific Resource Manager questions, you'd probably want to create a new thread over in the Database - General forum