This is a whole note. The whole note is represented by an oval or circle, though it's usually an oval. The whole note is equal to one note sounding for four beats. To see a demonstration of this, please click on the following link:

This is a half note, To create a half note, take the whole note and add a vertical line called a stem. The circular part is referred to as the note head. The half note is equal to a note sounding for two beats continuously. To see a demonstration of this, please click on the linke

This is a quarter note. To create a quarter note, take a half note and fill in the note head. The quarter note is equal to a note sounding for one beat. To see a demonstration of quarter notes, click on the following link: