Beginner Questions - which software and test cases?

Hi Members,

my name is Georg, i am from Germany and i study computer science.
At the moment, i make a practical training in a softwarehouse.

Originally, i am from poland, so sorry about my bad english!

For my future job, i want to take a (deeper) look into IT-Forensic.

Now, i am looking for some software (freeware if possible - but all so not so expensive Software) for making my first steps into IT-Forensics.

At the moment, i have downloaded and installed KALI (www.kali.org).

But i have no idear how to start…

So, my question is
1. Which software should i use/download?
1a. Is KALI ok to start?

2. Are there any "test cases" or "learning cases" with a story and a solution which i can download anywhere?
What i mean I download an image (or whatever) and read the story (for example There was a bank rubbery and the rubber looses his Notebook. Now, it is my job to find out something about the robber…).
Now, i investigate the notebook and find out what i can…
After this, i read the solution to check if i find out anything thats possible…

3. Are there any free tutorials/videos about "how to start", special for beginners?

I would really appreciate if anybody can help me a bit!

Thanks a lot!
Georg