Need a little help

I've been playing 5 years almost. I'm self taught, all I've ever done is learn songs (mainly metal) and i know a lot of techniques (pinch harmonics,bending etc..) but I've never understood how scales and chords work together and what scales to use with which chords. I've tried my best to understand but I've had no luck. I'm dying to understand how they all work and such because i am very interested in starting to write my own songs and improvise from scratch. If someone could help me out here, it'd be GREATLY appreciated.

http://www.all-guitar-chords.com/lesson.php?id=23
http://www.all-guitar-chords.com/lesson.php?id=26
http://www.all-guitar-chords.com/lesson.php?id=193

I think these lessons should come in handy to you, although I'm not sure how much of theory you understand already.
Personally, I've partially read the lessons I linked you to but I haven't tried too hard to fully understand them yet because I think I'm still not ready for that.

Anyway, for any questions you might have (especially when it comes to theory) I suggest you first take a look at the lessons' page (http://www.all-guitar-chords.com/guitar_lessons.php) because chances are good you might find an answer there.
Also, you might wanna search up your questions on the forum first since many questions are being asked over and over again which means it might already have been answered by one of the members. Not that we mind so much answering your questions but you'll be able to find an answer quicker and also read the following questions and answers about that particular subject.

I hope I was helpful to you. :D

Thanks a lot :D, this site has made me so much better than i was at understanding music and how things work. You've got me started, so thanks again, I appreciate it

Anytime man.