Confused about timing belt replacement

I just picked up a new timing belt.  My car has 140k and I don't know when it was changed.  Its also got a groove in the belt.  I was reading something about the tensioner.  My kit came with two wheels.  When people say you need to change the tensioner also, does that mean the wheel or the entire tension assembly?

the tensioner has the pulley(wheel) attached to it. you should change the whole assembly. i mean do it right the first time and you won't have to take the whole daym thing apart again later on lol. where did you get the kit from? they should give you instructions 

So your saying I should get the damper too?  It was off ebay...

Every kit I see just comes with the two pulleys and belt.

do you have a pics of this kit, ebay isnt the most reliable when it comes to parts. i also dont understand what oyu mean by 2 wheels.

Pulleys.  One is made in slovakia, the other in germany. The belt looks good.  The quality is fine. 

What I'm asking about is the damper.  Do I need to replace the damper?  None of the kits I've seen include it.