Hi,
can someone point me in the right direction regarding parameter and custom functions, I'm tried creating both mainly by trial
and error and can't quite get the hang of how and why to apply them, I've created some where I invoke the actual function and it returns an new table , other times I have to 'invoke' from the add column / invoke custom column.

I haven't included any examples but can do so if it would help what I'd like clarified ie sometimes everything is within the let

< let
name = ( a , b ) = > is a + b

in
name >

and other times it starts out side of let and in

< ( abc ) =>

Steps being made into function

in

last step >

and I'd like to find some information about how they differ?
Any suggestion, guidance welcome.

Richard.