need alot of work

ok so ive been playing guitar now for a while like 2 years i can play almost anything you through at me but i cant write becuase i dont know what structure to use to write metal riffs which is my style of music like i can write the riff just i have no idea what chords go with it nor where i can go from the note that im in like lets say im playing my riff in A minor i dont know if there is like a certain pattern you take for making the song go where you want it to im dedicated to learning but i just need a little help sometimes so please anyone who can give me a good answer i would really appreciate it

Start simple.... All songs follow some kind of pattern, but some the best just come from heart. If you start writing using the I,IV,V guitar chord pattern ie...,(C,F,G or G,C,D) which a lot of songs are written to you can add or subtract from there. Like adding a minor 3rd or a Major 7th, or dim chord in the progression. Yes there are technically rules, but use them as guide lines. Unless of course you are writing music for the Movie industry or jingles for commercials, those have finite patterns, and can not be changed, But if you are writting tunes for yourself, make them yours, by starting simple and expanding from there... Experiment, til you are satisfied.

Hope this helps

95Strat

What has helped me is learning songs that I find that fit my style and breakdown the form first. Like the riff is simply called "The RIFF" then there may be a verse form that I would call "Verse" then a "Chorus" then "Bridge" etc. This may give you ideas about structuring a song. Keep writing even if it's just riffs - some ideas may spark others that can be put together at a later date.
Keep working the creative mind!

All the best,
Joe Pinnavaia
http://www.guitarlessonsbuffalony.com
http://www.digital-nations.com/artists/testtuberhino