I know how you feel...everything is post, post, post...but really no good explanation for people who want to learn...
Think of Transits as Current planets' locations, and Natal as previous/birth planets' locations...
So Transits to Transits is current planetary alignments/aspects with other current planets...
While Transits to Natal is current planets' alignment/aspect in respect to where planets were previously...
Usually, people find the Natal planets' previous locations...based on the birth/natal date that they associate with the stock/pair...
However, this thread has advanced exponentially...and most current people here, are using transits to transits, current aspects to trade...along with some WEIRD calculations that I can't understand like...Square this, degree that, time this = price, if Y because time is @#!$
Hope that helps, because I'm a newbie to this as well...