There are many, many moving parts on a saxophone. Which buttons should you press? There is a "home key" set that is the basic finger positioning. The index, middle, and ring finger of each hand have three keys on either side of the saxophone that are the main keys. Most notes can be played with these keys. To play the note in a higher octave, add the button that corresponds to the left thumb. Your two pinkies have two or more buttons that can make a note sharp or flat.
The G note is usually the first note young players learn. It is also the first note on the concert B flat scale. The G note is played with the index, middle, and ring finger of your left hand. To play a higher G, add your left thumb.
The next note up from G, an A note, is the second note in the same scale. It is played with only the index and middle fingers of the left hand. To make the note higher, the same as with G, add the left thumb.