Click the blue-and-white target symbol. It's near the bottom-right corner of the map. This re-centers the map view to display your current location, which will be marked with a blue dot. If you haven't already enabled Location Services, you'll see an error telling you to enable them now.

On your computer, open Google Maps. Right-click the place or area on the map. This will open a pop-up window. You can find your latitude and longitude in decimal format at the top.