Hi Ive been playing for 16 years and I use arpeggios under what chord Im playing against. Look I once heard it said like this--Chords are frozen arpeggios and arpeggios are MELTED chords. SO under an Amin chord play Amin arp. then Dmin play Dmin arp. then E7 you play E7 arpeggio. This requires vast fretbord knowledge to switch under every chord. You also can mix it up and run scales into arp. and arp. into scales. Just be creative!
SO I would start by learning all 7 arpeggios for each note in the musical scale.(minor too) In all you should have 14 arpeggios to work with--the good news is many of them double up.-I mean you'll see the same ones over again. Trust me--this is what I did and after 1 year of forcing this into my brain and fingers my solo playing made a HUGE JUMP!! Just record any progression and try to play the arpeggio for the chord. This is what made Jerry Garcia such a master in the 70's. He would NAIL improved lines to chord changes like no other.
I hope this helps you understand why and how arpeggios are used in music.
Dan