Hi Jessica,
It is overwhelming at first.
What I suggest is to map out your lead lifecycle on PAPER. Discuss this internally with sales, marketing, etc. So for each stage, you need to know the criteria for a lead to enter/become a member of the Stage:
Anonymous=Anonymous
Prospect=leads not assigned who are in Lead Status=New
etc.
Then you can create a new RCM in Analytics with the appropriate Stages, Gates, SLAs, etc. I recommend keeping it simple like Marketo's examples.
When you have that in place, you can then build a set of lead lifecycle campaigns to help manage the transitions between stages. Check the docs on exactly what is required here.
To kick of the RCM modeler (make it active), you need a set of Smart Lists and Flows to assign leads to their current stages.
Once RCM is running, you can then use Revenue Stage filters and Flow actions to trigger campaigns, etc. to enhance nurturing programs or to start a series of welcome new customer emails.