how to use DocumentFormat.OpenXml.Office2013.Excel?

I'm new to the OpenXML SDK and I'm struggling to find documentation to get off the ground.  I can see some classes in this namespace that I think will be useful for my purposes, but how do I use them?  Example:

I'd like to get the OLAP level name of each slicer in my workbook.  I see classes called "SlicerCaches" and "SlicerCacheOlapLevelName".  Alright, so, I start with something like:

using (SpreadsheetDocument document = SpreadsheetDocument.Open(docName, true))
{
	WorkbookPart wbPart = document.WorkbookPart;
}

and now what?  i want to do something like:

foreach (SlicerCache slicerCache in wbPart.SlicerCaches)
{
	String levelName = slicerCache.SlicerCacheOlapLevelName.ToString();
}

but WorkbookPart has no "SlicerCaches" property.  I can see stuff like "SlicerCachePart" that comes from the "Packaging" namespace.  But how do I go about using the classes in the Office2013.Excel namespace?  Or, better yet, where can I find some samples that demonstrate this?