S2Graph provides a query DSL which has been reported to have a pretty steep learning curve.
One tip is to try to understand each features by projecting it to that of a RDBMS such MySQL.
This doesn't work all the time, but there are many similarities between S2Graph and a conventional RDBMS.
For example, S2Graphs "getEdges" is used to fetch data and traverse multiple steps. This is very similar to the "SELECT" query in MySQL.
Traversing each step is similar to "join" operation in RDBMS. One thing to note here is that users must start their traverse from smaller set to terminate BFS early as soon as possible.