i'm not sure if this belongs here or in the stringed instruments, but oh well, if i f**ked up just tell me.

anyway , i've been havin trouble writing sad slow like songs that you here in old love songs and like stairway to heaven or going to california, does anyone know how to make some of those slower sadder notes or chords?

agian , sorry if i f**ked up

i think this fits in both spots. i'm not much of a songwriter but i have friends who are. if memory serves me correctly a simple switch to a minor chord in a normal progression will darken the mood nicely.

Gennerally minor chords will create a sad sort of sound.
Try some progressions like:
Am, C, G, Em or
Am, C, G, F. perhaps alternate between the two.

Another thing that you might want to use is changing those minor chords a bit by adding the ninth, which in the case of Am is B. so... play this (frets):
0 : open e on first string
1 : c on second
4 : b on third
2 : e on fourth
0 : open a on fifth

this chord has got a dark and really unhappy sound. and that's moveable like a bar chord. If you are going to use this, remember to know when to back down, this chord can quickly loose it effect if you overuse it... sometimes the minor chord will sound fine unchanged.

Try playing with differnt time signatures too. Change the pulse of a piece, perhaps 4/4 and only strum on the whole beats, or in 6/8 and strum on all beats, take the tempo right down.

Appegiate the chords, like in stairway to heaven. Go up and down. That's a nice way to spread a chord out and make it last longer.