Thank you so much .. that truly did help a lot.
I will try your suggestion for books and wikepedia as well.
That indeed was a great help!!
Thanks again and have a lovely weekend
For natural deduction (of which Fitch calculus is one possible notation), you can look at references on Wikipedia. I also found this post on Lambda the Ultimate blog. I personally would lean to expositions by computer scientists rather than philosophers. In particular, I like Frank Pfenning's lecture notes.