Curly hair

I'd say I have 3a curls. I love them and want to make them the best they can be, but I can't afford all the different products so I just stick with the $3 shampoo and conditioner and Cantu hair products, which can range from $3-$6

My aunt sent me Not Your Mother's shampoo and 3 in 1 conditioner (rinse, leave-in, or co-wash)

How do you do a co-wash? I normally shampoo and condition my hair once a week, maybe twice if my scalp is irritated. Also I don't understand why the bottles only say to use a quarter size amount. Like do the people that make hair products realize not every one has thin chin length hair? My hair reaches my shoulders and thick.

Shampoo I use that amount maybe cause I don't need to be lathering up more than my scalp, but conditioner on the other hand I use a lot more