Okay, here goes. This may be long, but I'm bored so there:

Put the bike into a stand or a rack or hang it from the seat. Something so you can pedal and do some mechanics stuff.

I'm gonna have you completly redo your rear derailleur.

Shift into the middle chainring (up front) and the smallest cog.

Undo the rear shift cable and pedal the bike a wee bit.

Bend down and look at the bike from the rear. The upper jockey pully should be directly below and in line with the smallest cog. (In the same verticle plane)

If it's not, play around with the limit screw on your rear derailleur (RD). There are two of them. One is the inside stop the other is the outside. Play around and find out which one moves the rear derailleur in it's current position. Remember which one is which, because later, we're gonna adjust the other one. You'll actually see the derailleur move in as you screw it in. Adjust it so the rear derailleur lines up with the small cog.

Turn the barrel adjuster on your shifter and the rear of your RD in all the way, then out 1 full turn.

Pull the rear shift cable snug (not too tight) and tighten it down.

Now, while pedaling, shift up one gear. If the derailleur shifts up once, great! If not (while pedaling the bike) turn the barrel adjuster on the RD out (counter clock wise) until it shifts into the 2nd cog. Keep turning it until it starts to "want" to climb into the 3rd cog. Then turn the barrel adjuster back in (clockwise) until it stops "climbing" into 3. Usually about 3/4 to 1 turn back in.

Look at the back of the bike again. The derailleur should now be directly in line with the 2nd cog.

Now, check the inside stop. Shift all the way to the biggest cog. Try to overshift and force the chain off to the inside of the big cog. If you cannot, GOOD!

While pedaling, and shifting back and forth between the largest cog and the 2nd largest. turn the limit screw in to where the chain will NOT go into the largest cog.

If the chain doesn't want to easily go into the biggest cog, the limit screw is in too much. Turn the limit screw out until you can shift into the big cog.

Now, run through all the gears while pedaling. Up and down. Each shift should be crisp and clean. If it's slow to shift up from the small cogs, turn your barrel adjuster out in 1/4 turn increments.

If it shifts UP well, but is slow to shift back down, turn the barrel adjuster IN by 1/4 turns. Find a good compromise between the two.

Now, as a final check. Shift into the small cog in the back. Check the cable tension. Where the cable is exposed (between stops - no housing) you can pull on the cable. It should be taught, not tight, but not sloppy either.

Now that you've adjust the rear, go through and check how it shifts in each of the front chainring combos. Fiddle with the barrel adjuster till it's the best compromise!

L8R