More specific hints where needed:
1.) 4. Nc6 Specifically it loses a pawn if white plays correctly. Can you find a sequence of moves that ends up a pawn ahead for white?
2.) 5...Ba5 This move loses a whole piece if white plays correctly. If you have a real life board put the positions up and spend 10-15 minutes trying out different moves. You will learn a lot if you do.
3.) 8...Nb3 What pawns and pieces are unguarded? Can you make a move that makes another piece unguarded? There is a fork involved.
6.) 10...Bg4 Right, your bishop is attacked twice and only guarded once. That means you will lose that piece.
7.) 12. Qf4 Excellent! Now you just need to see it ingame next time.
10.) 16. e5 Look at white's king. What squares around it are weak? How many squares can it go to? Are any of them good? What would happen if you got your queen close? How can you get your queen close?
11.) 17...h5 Why is there a questionmark at the end of your sentance? You do see that after those moves black has a piece less than before? You did solve it, well done.
14.) 29. b5 I'm not sure what you mean by "backing into a corner" but if you meant bring pieces close to it and attack you are quite right. If you do have a chess board I suggest you put this position (after Qc5) up and take a close look. Here are some things you should ask youself: Who is better and why? Does black have any threats? If so, what are they? Can white do anything to meet those threats? Notice the plural, there can be more than one threat.
15.) 30...c5 correct
17.) 39...Qg4 I refer you to
Chess Wikipedia. Look up the rule "En passant". Qg4 does indeed allow a fork. If you haven't heard some of the terms I use such as "fork" use the chess wikipedia to look them up. In fact, I advice you to read it through anyway as there is some good stuff in there. h4 is a good idea. Why is is a good idea? (No, there is an even better move but it is hard to find so don't spend much time on that.)
16.) 35..Nxe2+ If you have spent some time looking at #14 you might have discovered why Qc5 was good. Is there any way you can achieve Qc5 in this position?
18.) 41...Qxb2+ You can take his knight off for free, yes. That's MUCH better than exchanging a queen for a queen, right?