First of all, you need to match the pipe size to the flue outlet size of your appliance, or you can go bigger, just not smaller.With a 6x10 flue, most likely you will need to use OVAL pipe in order to get it to fit down the chimney.
Most likely you have a round outlet on your appliance, so you use a special connector that transitions from the round outlet to the oval pipe.
Yes you should use a tee, a top plate (to seal the chimney at the top) and a chimney cap. In the area where the pipe runs up through the chimney at the bottom, you should seal that with household insulation (it won't burn). Just go and grab a small amout from your attic, if you don't have some readily available.
It is a simple installation that you can probably do yourself.
Be very careful when handling the stainless pipe, the edges when cut can be as sharp as a razor.
I hope the above helps and good luck!
