I will check if my computer has such a program later and do I really need to draw everything first? If so, I gotta practise drawing
Well, strictly speaking, you don't
have to be able to draw to animate. Most vector-based shows store all of the pieces of a character in a symbol library, and CGI uses rigged models, it's only if you wanted hand-drawn.
While that is true, FreckledOne, it is extremely time consuming to draw everything out on paper and scan it if you don't have an industrial scanner. If you wanted to go the traditional route you would also have to buy, build, or improvise a light box.
You can certainly animate in a regular art program, preferably a program that utilizes layers, and import the still frames into a different program to test them, but it would be extremely difficult to try to edit and compile a multiple shot animation that way. Even a freeware animation program would be more accessible than that, and would probably save a lot of time.
It does take a little while, but it is doable, and you could also use a digital camera to capture your drawings. For me, the lightbox kind of makes it harder to see what I'm drawing; I just flip through them by hand. I found this really cool turntable clipboard at Goodwill that I use a lot now. You could animate on the go with it!
And I have just the thing : http://www.pencil-animation.org/
I have... actually used this program to animate a T-Rex before. Hmmm, coincidence?
That animation is here, if anyone would like to view it: http://kelpgull.deviantart.com/art/Rexrun-302102665
That looks promising, but some of the examples they had on the website didn't work. If I didn't already have Flipbook I would try it. Pretty nice T-rex animation, there.

I especially like the angle as it runs towards the screen. I also have a small animation, if you would like to see. It's in my other fanart thread here:
http://z7.invisionfree.com/thegangoffive/i...showtopic=12811 It plays back kinda wonky; you might have to try a few times to get it to play back from the beginning.