As Panama Jack states there are principally two jetstream bands around the earth in each hemisphere caused by tropopause breaks. The Polar Front jetstreams are at about 60 degrees latitude, the Subtropical jetstreams at about 30 degrees latitude.
As the Coriolis force deflects the winds to the right in the Northern hemisphere and to the left in the Southern hemisphere, jetstreams always blow from West to East.
There are local jetstreams too, associated with fronts or low pressure areas.
To take advantage of the tailwind you should fly in the warm air as high as possible (you are out of the CAT area and the slope of the wind speeds is more shallow to the warm side).
To avoid headwind you should fly in the cold air as low as possible (you are out of the CAT area and wind speeds decrease very rapidly on the cold side).
Hope this helps!