Mount And Blade Social Key Mount And Blade Age Of Machinery Question...?

Mount and blade age of machinery question...? - mount and blade social key

I'm trying to get things catapaults and Mount and Blade, but I do not know where engineers set
Can someone tell me where and how u get em em must catapaults many? Moreover, if the fight actually

and how to operate machinery, or (I'm fairly new in this area)
thx!