Here is a quick overview of understanding Intervals and more importantly how to identify them. To really get to know intervals you must practise them throughout your instrument. Most importantly you must memorise these shapes the intervals create. This will make it easier to identify Chords/Arpeggios and scales. As you work on these intervals relate them to arpeggios. Things like knowing that a Major 7th chords has the Root (Starting note), Major 3rd, Perfect 5th and a Major 7th. This knowledge is fundamental basics of understanding music and how to comunicate it.