Photos SHOULD be taken with your smartphone and the app. You need to install the mobile app on your smartphone and use the app to take the photos. The app and the website are designed specifically to use photos that are automatically GPS tagged within the app, so that the GPS location is directly uploaded when you upload the images from the app. These photos and the records that are then transcribed are the primary data source for BG's mission.
It is possible to upload photos from a digital, but it is more trouble than it is worth, even if they are GPSd in your camera, that is lost when the image is uploaded as a secondary source. We don't recommend it for beginners.
Be sure to read all the FAQ on getting started in photos and transcribing before you take hundreds of images. Go to a local cemetery close to you and take about 20-30 photos then go to where you can use Wifi to upload them, and check them on your computer and transcrdibe them yourself. You will learn what you are doing right and what not to do again. Do not try to transcribe from the app/it is too buggy. After you have done a few dozen like this then you can up the number you do until you get better at the basics of the whole process.
Reply back here or post a new question if you need more help form us here in the community of users. And thanks for giving BG a try.