Funk arose as a music style in the 1970s and were originally associated with black music. You probably know how funk music sounds; otherwise, listen to artists such as James Brown, Marvin Gaye, Prince and Curtis Mayfield to get a sense of it. These are all examples of funk combined with soul. Funk can also be combined with blues (Kenny Wayne Shepherd and Johnny Lang are two names among many), or with rock (Red Hot Chile Peppers is a known example).
A central part of funk playing is to alternate the chord strumming with strumming on muted strings, which will result in scratch rhythms. Actually, you can in some parts of a song use more muted strokes than not.
Funk chords voicings
The 9th chord are one of the first chords you should learn if you are attempting to play funk on guitar. The 13th is a good second chord (the vesrion presented on the pictured is a voicing the the root on the 6th string omitted).
An easy way to start is with progressions such as A13 - D9 or Am7 - Dm7 (standard barre chords can be used).
Funk chords voicings
The chord diagrams above lacks indication of which tone it is and only presenting the chord shape. Since these chords are movable you can use them for all tones and if you are unsure of fret positions you can use the presented lists below.
These chords are all alternatives of more standard ways to play 9th, 13th, 7th and minor 7th, which deliver a funkier sound to them.
These are all voicings which excludes (!) the root note. This is strange for sure, but the easiest way to comprehend this is to look at these chords as fragmented versions of the typical 9th chord, by which B9 are played as X21222. See the list below:
B9: XXX222 (or X21222)
C9: XXX333 (or X32333)
D9: XXX555 (or X54555)
E9: XXX777 (or X76777)
F9: XXX888 (or X87888)
G9: X X X 10 10 10 (or X 10 9 10 10 10)
B13: XXX224 (or X21224)
C13: XXX335 (or X32335)
D13: XXX557 (or X54557)
E13: XXX779 (or X76779)
F13: XXX88 10 (or X 8 7 8 8 10)
G13: X X X 10 10 12 (or X 10 9 10 10 12)
Bm7: XXX232 (or X2X232)
Cm7: XXX343 (or X3X343)
Dm7: XXX565 (or X5X565)
Em7: XXX787 (or X7X787)
Fm7: XXX898 (or X8XX898)
Gm7: X X X 10 11 10 (or X 10 X 10 11 10)
Examples of progressions suitable for funk guitar:
Bm7 - E9 - D9
One easy way to get started and get some funky sound from your guitar is just to shift between a 9th and a 13th chord. It is easy, only one finger needs to be moved. You could also slide into the 9th chord from one fret below.