So you are facing any problem in doing so.
Identify the key fields in both the tables and join them accordingly.
Or is it something else you are looking for
When joining gl to po tables you will need to join the gl_je_lines table to gl_import_references by je_header_id and je_line number. You then need to join the gl_import_references table to po.rcv_receiving_sub_ledger by gl_sl_link_id.
This will then allow you to add remaining po tables (po_distributions_all, po_headers_all and finally po_vendors) to get the vendor details you need.
I suggest you take a look at the Applications Electronic Technical Reference Manuals (eTRM) on Oracle Metalink to give you an understanding of the joins (login required).
That will work for purchase order accruals, but not for any payables data. To me, you are better off doing a separate UNION query for each journal source (Purchasing, Payables invoices, Payables payments, etc.)