It would be awesome if you could explain this to me like you would a young child lol
So you start out with barley water. Barley water is food for yeast. Yeast eats barley water for dinner and grows big and strong. If you have one plate of dinner and lots of yeasts, they have to share the dinner so none of them gets enough food. If you have too many plates of dinner, they can't eat all of it before they get tired.
ckpash just do what I advised earlier for this beer.
1) Add 3.5 oz of DME to 1 qt water. Boil it for a few minutes, chill, pitch the smack pack. Let it ferment out.
2) Put it in the fridge for 24-48 hours and let all the yeast settle out. Then decant off the starter beer so you just have the yeast cake at the bottom.
3) Cook up another batch of starter wort with 13 oz of DME in 4 qts water. You want to end up with 4 qts of final volume give or take but you'll lose some volume during your short boil of the starter wort.
4) Chill that down and add to the yeast cake. Shake/swirl it up and then let that ferment out. Repeat the chill/decant routine and then pitch to your beer.
Get this starter under your belt and then worry about figuring out the differences in results between intermittent shaking and a stir plate. Don't worry too much about exact volumes and gravities this time around. You're making a starter and you'll get a good pitch of yeast even if it's not exactly right. As long as your sanitation practices are good you'll be well ahead of the game and will make good beer. RDWHAHB.