C D E F G A B C
Now count up 3 scale degrees counting C as one. So you would go C (1) D (2) and E (3). So E will be your third above C. Now count up 5 scale degrees counting C as one. So you would go C (1) D (2) E (3) F (4) G (5). So G would be the fifth above C. So your chord would be C E G with E being a third above and G being a 5th above. This is a C major chord.
C D E F G A B C
1 3 5
Now if you started on D and counted up a 3rd and a 5th you have a d minor chord and if you started on E you would create a e minor chord. If you started on F or G you would create major chords and if you started on A you would create a minor. AS LONG AS YOU STAY IN THE KEY SIGNATURE... That is key. There is what they call "chord quality of a major scale". let me use C major as a example.
CEG is a major I
DFA is a minor ii
EGB is a minor iii
FAC is a major IV
GBD is a major V
ACE is a minor vi
BDF is a diminished viiO
Now go to your bass and start on C, third fret of your A string and build the C major triad. Think major scale pattern. So you play second finger 3rd fret on A string, then first finger second fret D string, then pinky 5th fret D string. This will outline a C major chord. Here is a chart for major chords. Get to know these then go to minor chords.
Major chord table
| Chord | Root | Major third | Perfect fifth |
|---|---|---|---|
| C | C | E | G |
| C♯ | C♯ | E♯ (F) | G♯ |
| D♭ | D♭ | F | A♭ |
| D | D | F♯ | A |
| D♯ | D♯ | F (G) | A♯ |
| E♭ | E♭ | G | B♭ |
| E | E | G♯ | B |
| F | F | A | C |
| F♯ | F♯ | A♯ | C♯ |
| G♭ | G♭ | B♭ | D♭ |
| G | G | B | D |
| G♯ | G♯ | B♯ (C) | D♯ |
| A♭ | A♭ | C | E♭ |
| A | A | C♯ | E |
| A♯ | A♯ | C (D) | E♯ (F) |
| B♭ | B♭ | D | F |
| B | B | D♯ | F♯ |
