The miBUGLE (pronounced my-BUGLE) application is a relatively easy tool to use. There are only seven keys available which performs the actions and plays the sounds.
You may or may not have heard of the word "embouchure". According to Webster's Dictionary embouchure means "the position and use of the lips, tongue, and teeth in playing a wind instrument". Being that you are not going to be using your lips or tongue or even teeth on your iPhone or iPod Touch, then the application needs to do it for you.
There are two images below. The first image shows the notes of "The Natural Bugle Scale". The second image shows the front of the application and the notes associated them. All you have to do is blow into the microphone and press one of the seven keys. If you don't want to blow into the microphone, then you can change the AutoBlow setting located on the INFO screen.
http://www.usscouts.org/mb/bugle_calls.asp#first