hi, i'm not a so good at animating (don't know anything about it) do you know some good and easy to learn program for animating a character? something that can be used with unity
Learning how to animate isn't easy and requires a lot of experience. Personally I can recommend blender, it's free to download and has a lot of good tutorials. Look at blendercookie.com and learn how to model and animate an alien. Blender integrates very well with Unity. The .blend files are imported without need to convert them to another format.
3ds Max is also a good program to use. It looks good and has tons of tutorials all over the web. The only downside is that you can only get the 30-day trial unless you are a student, in which case you can potentially gain access to all Autodesk products by signing up using your school email. I haven't tried this myself as of yet.