FTM silly question -wet diaper?

L

This is probably obvious to a lot of you but I am pregnant with my first kids (twins!) and it’s all new. We are going to cloth diaper. Some friends gave us a pack of newborn disposables and I was playing around with one and it has that little yellow line on the bottom that turns blue (I think) when wet.

So with cloth diapers, how do you tell if the diaper is wet (just pee). Smell? Or do you have to feel for it? Or just a fussy baby?