Can't add much to what the others have said. I do not know how examination in chief (for getting evidence of your own witnesses out) and cross examination (for challenging the evidence of your opponent) works in USA. Here, for exam in chief (XIC) you can only used open questions and must not "lead" the witness. Ie you must not ask questions that suggest a particular answer. A good guide is to start your questions with "Who, what, why, when, where, how".
In cross exam (xx) you should used closed questions and not give the witness any room for manoevre. If you can try and keep your questions to those that require a "yes/no" answer, that is sometimes a useful way of limiting the witness's impact. The point of xx is to put your case (you MUST put your case to the witness), you should also test the evidence by highlighting inconsistencies and impossibilities. If possible you should also attack their credibility. If you can get the witness to tell you a big fib (which you can prove to be a fib), his credibility usually goes straight down the pan with a jury.
But remember, you should never ask a question to which you do not already know the answer.