Go check out how you are doing on each fight. Check what you are standing in. Check what button you should be pressing. Try and better your self to the best of your ability.
People are always struggling with trying to figure out how this bloody system works. Well here it is.. a very good video on Warcraft logs for beginners this is a step by step guide on how to use logs and better understand it.
With all of the above being said on how to look at your Warcraft Log. Now you can Link your warcraft logs into WoW Analyzer
What WoW Analyzer does, is it takes your Warcraft Log.. and breaks it down to see what you did Wrong.. as well as Right. Now with that said.. its not always 100% proper and you need to take this with a grain of salt.. But... it will assist you. It works.. it helped me out huge.
Take the Warcraft Log of that day you want to look at that you where in.. Copy the URL.. Paste in the WoW Analyzer and poof.... check it out. If you have questions please ask.