In Jainism, the customary practice after death is cremation of the body (antyeshti). As for what to do with the ashes:

• The ashes are usually treated with reverence. A common practice is asthi visarjan (immersion of the ashes) in flowing water such as a river or sea, or placing the ashes in the earth to dissolve gradually. The key is to dispose of them with respect and to aid the departed soul's onward journey.
• Burial of the body itself is not the standard Jain practice; cremation is the preferred and traditional method.

There can be small differences between Digambar and Shwetambar communities in specific rites or sequence, but both traditions generally follow cremation and a respectful disposal of the asthi. If you are planning a ceremony, consult a local Jain temple priest or community elder to follow the exact customs of your lineage.