A Major 2nd example would be from Middle C up to the next note D.
A Major 3rd example would from Middle C up to the next E.
Once learned, these intervals are the foundation to build upon to learn to read music on any instrument.
The practice tips for Mixed Up Intervals will help you mentally prepare yourself before you start to learn the piece. Begin by placing both hands in the C position in the middle of you piano keyboard. Your right hand thumb should be on middle C. Your left hand 5th finger should be on Bass C. Bass C is the first C below middle C.
Although it may seem silly it is still a good idea to speak the words or say the letter name of each note as you play. It simply helps you track your place visually within each measure as you proceed through the piece. It also keeps your tempo or speed at a slower pace which is better at first.
Be aware that the music intervals of a 2nd and a 3rd are both found in this piano exercise. Each interval or distance between notes is always moving either upward or downward.
Playing along with the video below several times will increase your learning curve enormously. Take the few minutes now to listen to the video in its entirety and then repeat it to play along at least 3 times. The payoff in your ability to read music will be quite worth the time spent doing this simple music interval exercise.