I proudly present: ShowScale.com, the ultimate (free) tool to help you find the music scale or key you are working in. With a few clicks on the notes you are playing the tool will determine what scale(s) fits your song. No music theory is required for using this tool.
You can also select a key from the drop-down menu, when a scale is selected the tool will display the right notes.
I hope this tool will help you learn about music scales.