Sql 2012 table partition

Hi,
I have a table partition, when each partition has its own filegroup-one file.
before the insert statement , how i can know where the row is going to be site ?

what is the meaning of "next use" in alter scheme ?

thanks

When you can identify a row or set of rows already in the table. Please try this sample query.

SELECT $PARTITION
[PartitionFunctionName]

(partitioning_Column)
  FROM dbo.table
  WHERE <clause to identify rows>;

To know more about partitioning please go this one it may be helpful to you. https://msdn.microsoft.com/en-us/library/ms188071.aspx