Strawn of Pennsylvania and Indiana

I have just signed into this page so be patient with me please.
I am trying to find a marriage between William G Marshall and Christiana Strawn.
Both were born in Pennsylvania and both died in Indiana.
William G Marshall B:14 DEC 1789 Pennsylvania D:7 August 1872 Spencer, Owen, Indiana, USA.
Christina Strawn B:10 AUG 1798 Perryopolis, Fayette, Pennsylvania, USA D:19 NOV 1885 Richland City, Monroe, Indiana, USA.
This is what I found on there marriage but no proof:
Marriage 24 Aug 1815 "¢ Perryopolis, Fayette, Pennsylvania, USA. I would appreciate any help. She was my 3rd great grandmother.

Christinas parents:

Job Strawn II
1760"“1821

Mary Cooper
1775"“1812

Jobs parents

Jacob Strawhen Sr
1717"“1800

Christiana Pursell
1721"“1805

Thank you Davy Jo Williams