How do I adjust the chain so that it stops ticking in certain gears?

It doesn't sound like the problem is in the chain but in one of the 2 bits of gear-change hardware, the derailleurs.
As the ticking is only in the top 7 gears, then it probably means your front derailleur needs a slight adjustment.
On top of the front derailleur, just where it wraps around the chain, you should find 2 small screws about 5mm/1/4 " apart. On most Shimano gear systems, the screw closest to the bike usually adjusts the top front gear.
If it's the outside of the chain that's rubbing the mechanism, then turning the screw clockwise will move the mechanism away from the frame.It shouldn't need more than a couple of revolutions at most.
Do it in 1/4 turns and then give the bike a test.
If the inside of the chain is rubbing, then turn the screw anti-clockwise.

Big Softy
July 2006