I must agree,
in the wise words of the Ventures,
"walk,don't run"
or to Quote,"What About Bob?".. BABY STEPS....!
if u want to expand your musical vocabulary,so to speak, Jazz is the right direction,
the way out of the "pentatonic box"..

BUT..u have a lot to learn first.
take it slowly,methodically..and GET A GUITAR.
1.BUY A GUITAR
I'd suggest having a friend or instructor chart out some slightly more "interesting" guitar chords for you,Get a cheap guitar if you haven't got one.
If you you can recognize the sound of major vs a Minor chord..that's number one,always.
before u tackle jazz,learn major,minor chords and scales on a guitar and bass.
learn to spot them in music,what do maj or min chords
sound and feel like?
have somebody chart out some:
seventh chords
minor sevenths,
major sevenths,
diminished,
and augmented chords.
learn them in the same key first,maybe all in A.
(A minor 7,A major 7,etc)
learn them well, how to play them on a guitar,
2. learn to recognize them.
What does a major seventh sound/feel like??
or a diminished?..
..learn to spot the chords in songs you know..
for instance,"Mercy mercy(The Ecology)" by Marvin Gaye..
(the,"Brother,Brother..song")
that song has a Major 7th feel,it's all major seventh,baby..
or "Eyes of the World" by Grateful Dead,another Maj 7th song.
3. after you can spot the chords,and you know them on guitar,
learn the full scales..
go through my list,learn each one in scale form.those are the basics ones.
or,in other words,this is where u go,after you can spot major and minor.
Once you can play the chords,recognize their sounds..
and play the full scale on your bass...
4. you can try to incorporate them in your playing. use a little diminished scale here and there,try a minor arpeggio at the end of a minor-ish song..experiment with the scales.
5. when u know the chords I listed, you can try finding other versions of the same chords on the guitar neck.
There are many,many versions of an "A diminished" chord,
all over the fretboard,many forms and shapes to try,of the SAME chord!..
..Try linking your new guitar chords together,(the min7,maj 7,dim,etc..)
6.print some simple jazz standards off the net,(with guitar chords listed),
and follow the chords on your guitar,until you're playing songs.
remember!..the four lowest strings of these guitar chords can be used as
BASS CHORDS!
BOTTOM LINE??...once you can play a simple jazz chord progression on guitar,
you can tackle the bass part,
jazz bass is hard,
they tend to be walking bass parts,
where u need to know the scales so well,by heart,that you can improvise quickly enough to stay on a quarter-note walking bass pattern.
This requires alot of time studying the scales,and also listening to jazz,learning the cliches,and just absorbing alot of walking bass parts.
IMO, if u recognize the chords,and can play them,you can then understand a jazz bassline, If u fill your Ipod up with a truckload of Jazz,that's gonna help,
but studying,playing and seeing the chords,will help you grasp what they really are.