https://maxroll.gg/d4/build-guides/ball-lightning-sorcerer-guide#endgame-gear-&-skill-progression-headerThat should help you when it comes to the actual build and affixes you should be looking for.
Also, if you completed the campaign, you are probably still low level. It is hard to be a ball lightning sorc at a low level due to mana and cool down issues.
I would just play chain lightning or other easy leveling builds until you get high enough level to effectively play as a ball sorc. I think lvl 60-70 is a good time to play as one.