Here is the page that Belyayevs-Fox is talking about:
https://www.newgrounds.com/wiki/creator-resources/animation-resources
I'd recommend krita since it can double as an art and animation program plus it's also free. Blender can also be a good choice, I heard it can do 2d and 3d animation, and it is also free.
Belyaevs-Fox
Newgrounds has a creators resources page where you can find links to good animation programs for use.
AlexTheFish
thx i will have a look at that