To use WoWAnalyzer, paste your Warcraft Logs report URL into the field on WoWAnalyzer’s home page
. Then pick the fight you want to analyze, and select your character. That's it! The analyzer should do the rest of the work. Alternatively, you can search for your character's logs directly on WoWAnalyzer using the character search feature on the front page.
Once you have a fight loaded into WoWAnalyzer, you’ll be presented with either a Checklist, or a Suggestions list. Not all specs support the Checklist yet, but don't worry - all the same information is provided in the Suggestions list, it's just a different presentation format (in fact it's a good idea to be familiar with Suggestions even if the Checklist is present, as it will sometimes contain tips that aren't covered by the Checklist). These lists will give you a summary of how well you are performing, whether you are making any mistakes (in the Checklist, issues are denoted with the red X) and suggestions on how to address those mistakes. These should be your first steps if you are new to a spec or are unsure what you should be focusing on, as they are typically the highest priority issues. In the Suggestions list, suggestions marked as “Major” should be your top priority.