You can add a memorial buried in a cemetery using the Find a Grave app. For information about adding memorials not buried in a cemetery, click here.
To contribute, first sign in. Open the app and tap on Memorials in the bottom menu. Tap 'Add Memorial." Choose the cemetery using the search fields and the cemetery map. Tap on the cemetery to choose it.
Fill in the fields for the memorial. Tap Create to add the memorial to the cemetery.