Allocated Parts

I am a new user of Vantage 6.1 and Crystal Reports 8.5. I am trying to
write a report that shows the Part#, Part Description, Qty. Reserved,
and the Job or Sales Order # that the part is reserved or allocated

I have tried numerous attempts at joining the tables, without success.
The most recent being:

PartAlloc -> PartWhse -> OrderDtl -> JobMtl

Can someone please tell me, what is the "key" to understanding the flow
of the table joins? And, how each field relates within the various

Thank you.