how do you gain settlers?

[Lucky-E]

been a long time since i played- just going over some campaign missions-
tablet says "raise 50 setters" i had 47 .... i built a couple houses... now I have 0

?!?! errrm .... what am I missing?

[Dreadnought]

build a school->kids turn into adults(settlers)

any *extra* settler will remain *stored* until you build a new house

aaaparently :3

[Capitán Alatriste]

Build a couple of schools. They attract settlers by educating children and enter it into the settler resource pool