#1
Ok guys, I've got a few questions about these altered chords.

First off, what are the intervals? (Like, major is 1 3 5 etc etc)

Second, a fingering in how to play it? Wiki's definition shows it to be more than 6 notes.

Third, how to use it in context and resolve it? I was looking at Guthrie Govan's "Wonderful Slippery Thing" and he uses a progression that looks like Bm7, D9, Gmaj7 and F#altered.

Thanks.
#3
i think it means to add an altered tension, like a # or Flat 9. #11(tritone), #13 etc.
please dont go on my word alone though, as I am not positive.
#5
Altered is referring to altered dominant chords. The possible unaltered extensions of an X7 chord are 9, 11 (though it's used much less than the others), and 13. Now, consider that a #11 is enharmonic with a b5, a b13 is enharmonic with a #5, and a #13 is enharmonic with a b7, and you realize that the available altered extensions are: b9, #9, b5, and #5. The reason why we can use these notes that are 'out' is because an X7alt functions as a V7; the function of a V7 is to create tension in anticipation of a resolution. It follows that creating more tension with the V7 will make the subsequent resolution more dramatic, and so we say that a V7 can be extended and altered however the player would like.

An X7alt refers to almost any combination of these alterations. Which alterations you use depends on the melody of the song. A general rule of thumb is this: don't include notes that would create a minor 2nd/9th interval with a melody note. So if the chord were G7alt, and the melody was a single whole-note D, you probably wouldn't want to include the b5 (Db) in your chord. Here are some possible (rootless) voicings of G7alt:

e--4--5--6--4---6--4--5--6-----
B--2--2--2--3---3--4--4--4-----
G--4--4--4--4---4--4--4--4-----
D--3--3--3--3---3--3--3--3-----
A--------------------------------
E--------------------------------

In order, they are:
G7b5b9
G9b5
G7b5#9
G7b9
G7#9
G7#5b9
G9#5
G7#5#9
It would probably be a good idea to systematically invert each of these voicings. It's pretty easy, actually. If we went with the G7b5#9 chord, we could get these inversions: (to get from the first voicing to the second: Start with the notes F and B: move them both up an octave to the B and E strings, respectively. Move the A# down an octave to the D string. Move the Db to the G string.)

e--6--7--6--9---13--------
B--2--6--6--11--12---------
G--4--6--6--10--15---------
D--3--8--9--9---11--------
A--------------------------
E--------------------------

When you do it with all of them, you'll start to see equivalents and possible substitutions. Try it out.

I didn't look at the Guthrie piece, but analyze the melody and experiment with the possible extensions and alterations to see which ones work and which ones don't.
known as Jeff when it really matters