Someone I know went to prison few years ago, what he told me after the initial shock and routine, most difficult thing to manage is time, there isn't much to do, what to do all day? people are busy in outside life but when they go in its a shock. I don't know about your country but in Europe they should have "learning new skills" opportunities. apart from that books will help tremendously, start with religious books, Bible/Quran/Buddhism etc, so you can develop faith, faith which will help when you go through emotions, then build up on that, then whatever book interest you, then depends, law books might be another, then self help books, then other interests, make a habit of reading books for few hours a day. 


For you mate: Look you need to be strong, its all pre destined what's gonna happen is gonna happen, if you think he is wrongly accused, you should fight for it, if you think  the conviction was right, learn and move on. There is no reason to lament or fret, there are worse places than prisons. Develop a strong personality, so nobody bothers you, don't get into depression, don't drink excessively or drugs and stuff. if you going through specific problem write it here, or feel free to pm me, and remember you can always go to the help groups around you, but if you are gonna face the other way, the world will feel miserable, all the support is at arms length way. You can do it.