To find the owner of the military dog tags, you need to write down where you found the tags on a piece of paper and also include your full contact information. Then, put the letter and the dog tags into an envelope and address it to the Secretary of Defense, and afterwards take it to the Post Office. For more information, go to http://www.ehow.com/how_7739697_can-military-dog-tags-owner.html.
There should be an ID # on thetags starting with RA or US that # will identify the person. You can drop them at a army recruiting office and they will contact the owner, but I don't believe they will give you that information