How does it know how to gps around? From what I know everything down there is a chemical reaction with some minimal physical motion, but how do you program it to know where to change and what and how.
Add gene has a great guide as to what goes on at the molecular level: https://www.addgene.org/guides/crispr/
Essentially you can design an rna molecular that contains a 20 nucleotide long sequence that can target your region of interest, with the caveat that there is a standard recognition sequence proximal to your sequence of interest (PAM sequence)
> until it finds the exact DNA letter that needs to be changed.
This pine is disingenuous (at best). There is no way of guaranteeing where the DNA is inserted. It is designed to only slot into a very specific portion of the DNA but they don't have a way to control that precisely, the accuracy is high but "exact DNA letter" is skipping over a few pretty important details.
To be clear I'm not saying it is ineffective or unsafe, only that the claim made is marketing speak and not actually true.