What is a good website that helps you compose guitar songs with chords by choosing a key?

Question

like you know, you choose the key you are in , and then it gives you the choices of chords you can use in that key?

Answer 1

Probably, but it's easier if I write it here than trawl the net.

Your most important chords are I IV and V - that means the chords of the first, fourth and fifth degrees of the scale. For C major that would be

C D E F G A B
I (ii) (iii) IV V (vi) (vii)

C F and G

Your next most important chords are vi and iii - these are your minor chords, so in C that's Am and Em.

By important I mean "most frequently used" - though of course you could write a piece of music that uses just chords I, vi and V, and doesn't use IV at all.

As an aside - I'm using numerals rather than chord names because the numerals apply to ALL keys - I IV and V in B would be B E and F# for instance. Ones in capital numerals mean major, ones in lower case mean minor.

There are hundreds and hundreds of different combinations of chords, even just using those 5. For instance one frequently used chord progression is I V vi IV, another is I IV I V, yet another is vi I V vi vi III vi - try fiddling with the ones I've given you and you should come up with something. If the numerals system is confusing then use the chords

E A B C#m and F#m to begin with.

I hope you get somewhere!