Hey Judge. I'm going to post basics. War is pretty easy when you play it a bit. You can click on the guild war icon and read an explanation of what to do. Some people in my guild found it difficult to understand, so the basics: go into war icon, look for the tab at the bottom and set your defenses. As with all game modes, having the post powerful lineups are not necessarily the best choices. My guild used the first week it came out as a trial run trying out different attack lineups and defense.
Your guild leader or champion will have to use one if the tickets, which are available every 12 hours to start war. An officer can start war, but cannot end one. After one if the guild leaders begins a war, and you've set up defenses, pick a tower close to your level and hero stars. Always go for a sure win. If you lose a match, it hurts you and your team. Select someone to attack, then choose heroes you think can beat both the enemy defenses. Then go attack.
This is war in a nutshell. It's pretty fun and once you get the hang if it, also easy to win. Hope this answered your questions.