I could do a write up, but it might be just as easy for you to search this forum for "band adjustment", there has been a lot of talk/write ups about it. T/V cable has been mentioned too.
If you feel you need to move or just check the adjustment, make sure you mark the cable first so you can at least go back to where it was. A lot of people prefer a cable thats a couple "clicks" tight, for slightly firmer shifts, and to hold gears a little longer before up shifting. Keep in mind T/V cable/pressure does not control the 3/4-4/3 shift.
Where the cable mounts to the bracket at the throttle linkage you will see a white plastic clip, carefully pry that clip up to allow the cable housing to move back and forth. I know some people have also adjusted/bent the bracket where the cable mounts on the trans too for adjustments.
Move the cable housing back (away from throttle body will increase T/V pressure or raise shift points, side affects can also create sensitive downshifts and harsh engagements and harsh upshifts.
Move the cable forward (toward throttle body) will lower T/V pressure or lower shift points, side affects can be early/quick upshifts, no or excessive throttle to make downshifts, slip/shuttle shifts, and slipping trans.
Most typical symtoms of a loose T/V cable would be quick up shifting through the gears, and possible slipping manily during shifts. Along with lack of downshifting under load.
Most typical symtoms of a too tight cable would be, late up shifting through the gears at light throttle, harsh engagements. Also may downshift easily with little throttle input.