Bass players tend not to play chords but there's no denying they're fun; not to mention useful to know. This video lesson takes you through the key of G major and harmonises it to get a set of seven different chords (see below the video for the diagram). Pair this lesson with the one on the seven arpeggios of C major.
G Major Harmonised In Tenths
Download the PDF: G Major Scale In 10ths
Roman Numerals (Nashville Number System)
Musicians number the chords using Roman numerals with lowercase denoting minor and uppercase for major chords:
I ii iii IV V vi vii
Take these shapes and experiment. Put them in different orders and you get chord progressions. Write a few then add some rhythm and organise your progressions into some sort of structure. You will have the beginnings of a piece of music.
Learning how melodies work over the top of the chords will give you another important element of music. This example is in the key of G major/E minor so use those scales as well as the pentatonic scales and you'll be in business.
Now go and write your next hit!