Where To Start?

Hi my names Casey and just joined this site. I was looking for a great resource for lessons and found this site by chance. I immediately was blown away by the amount of diverse and well detailed lessons so I decided to join. Ive been playing for about 8 years mostly learning songs along the styles of august burns red, between the buried and me and others in the progressive metalcore genre but never really learned the music theory behind it. What would be a good place to start learning to better understand what scales, modes and other important aspects of this style of music? Thanks for your help, really look forward to what this site has to offer!