What are you having problems with? Modes and Chords right now.
Modes are moods of a scale. Used in melody if you are
not playing melody you do not need to get off into modes. I see little value for modes in accompaniment bass. The melodic guys/gals see otherwise. Since you asked let's get modes out of the way I know you will just keep asking because the guitar guy/gals have told you about them saying things like; "Man you gotta know your modes." So hang on.....
Two ways to play modes; 1) Relative where the mode notes stay the same and you walk the key. C Ionian is the same as the C major scale. D Dorian is the C major scale started on the D note and played D to D. Phrygian is the same C major scale but this time started on the E played E to E. Etc. Then there is the second way and this is called Parallel modes. Here the key stays the same and the notes change. Both get you to the same spot, you've just taken different roads getting there. Relative is easy to teach, however, I find it hard in the middle of something remembering if I need D to D or E to E.. So I go the Parallel way. For example:
* C Ionian is the C major scale. C-D-E-F-G-A-B
* C Lydian is the C major scale with the 4th degree sharped. C-D-E-F#-G-A-B and we normally notate this in scale degree numbers R-2-3-#4-5-6-7. Makes it easier to use on the fly in a song or whatever. If you want the sound of Lydian sharp the 4. Yes it's that simple.
* C Mixolydian is the C major scale with the 7th degree flatted. R-2-3-4-5-6-b7. That is the major modes of the C major scale.
The minor modes are:
* C Aeolian is the same notes as the C major scale with the 3, 6 & 7 flatted, i.e. which is the same as the C natural minor scale. R-2-b3-4-5-b6-b7.
* C Dorian is the same notes as the C natural minor scale with the b6 sharped to a natural 6. R-2-b3-4-5-6-b7.
* C Phrygian is the C natural minor scale with a flatted 2. R-b2-b3-4-5-b6-b7.
* C Locrian is the C natural minor with the 2 and 5 flatted. R-2-b3-4-b5-b6-b7.
How to use them - each has a mood. If you want an up-beat sound use Ionian. If you want a major day dreamy sound use Lydian. If you want a Latin or Blues sound use Mixolydian. The Chord
vamp you play over helps give it the sound you are looking for. Aeolian is said to be sad, Dorian is an attractive jazz sound, Phrygian gives a Middle Eastern sound and Locrian will give a dark and tense sound. So if you need one of these sounds help yourself to that mode. Google modal vamps for the rest of the story.
Modal Harmony
Word of caution; some have you play Ionian over the I chord, Dorian over a minor chord and Mixolydian over the V7 chord. When playing a mode over a chord progression you are going to hear the tonal center of the progression, the modal sound has a hard time cutting through that V-I tonal sound. Plus with a chord progression of I-IV-V7 the modal mood of the song has changed three times, I doubt any song changing it's mood three times and certainly not in one verse. Solution to this is to pick one mode and play your mode over a one or two chord modal vamp. Here is a video of modal vamps. Ionian from 0 to 2:11 then it changes to Dorian - listen for the modal vamp change for Dorian (a minor mode) and then at 4:03 for Phrygian and I think this will begin to make since. Play Ionian over the Ionian vamp, Dorian over the Dorian vamp, etc.
Chords. Chords do two things; one deals with movement; I (rest), IV (tension), V (climax) and the second deals with harmonization. The songwriter will place a chord at specific spots in a song to harmonize the melody. If the melody and the chord share like notes harmonization happens. So it's a balancing act between movement and harmony.
Chords are made from the scale being used. Normally this is every other note in the scale, i.e. the 1-3-5-7 in this paper I will not go above the 7th note. For example:
Basic Chords R stands for the root or 1st note in the chord.
- Major Triad = R-3-5 aka C
- Minor Triad = R-b3-5 aka Cm
- Diminished Chord = R-b3-b5 aka Cdim
7th Chords
- Maj7 = R-3-5-7 aka Cmaj7
- Minor 7 = R-b3-5-b7 aka Cm7
- Dominant 7 = R-3-5-b7 aka C7
- ½ diminished = R-b3-b5-b7 aka Cm7b5
- Full diminished = R-b3-b5-bb7 aka Co
Is there more? Yes, books have been written on each, but, that is enough for now. Ask
specific questions.