Hi Claudia.
Are you using "AF" to stand for "Adobe Flash" Or "AFter effects"?
If you are trying to composite character animation over a background in After Effects, yes, it is a fantastic application for it.
You can create many types of backdrops easily (and very easy to modify elements back/forth from Photoshop)
As for character animation, there are multiple standard tools within After Effects. There are also third party plugins that may help you.
One plugin that I like to use for character animation is DUIK. DuDuF R&D » Duik – DuDuF IK Tools
(free)
Another plugin that is excellent is Mettle Freeform http://www.mettle.com/tutorials-digieffects-freeform-freeform-v2/
($99)