Joe Rich gave you some good information. Go to the Family History site . It is free to join and there is a lot of data available. Start with yourself and work backward through the generations. Many times marriage and death certificates ,as well as birth certificates, will give you data as to who parents were.Census records can help to find where your ancestors might be from and who was living in a certain household on the date of the census. The last census released was the 1940 census and it is a gold mind of information. Keep working at it and you will find something.
Looking at the uniform, I would say it is a WWI American uniform. Go to google images and see if does not look the same to you.