Although we are all Amtrak train enthusiasts in one way or another, very few of the members here have any Amtrak employment history, although there are a few retirees who are members.
I hope you will get some advice here, but it might be as well to google your question?
I imagine Amtrak will not expect you to know anything at all about the job, and will take you through the induction and training process, so just try to relax.
Expect to have a lot of "rules" and "signals" to memorize and learn as well as successfully pass to continue your employment. Take your studying seriously...