ELI5: How are Dire Wolves’ DNA (or any) “coded”?

As you may have seen, scientists recently “de-extinct” dire wolves through “editing genetic code of regular wolves”.

But what does that actually look like? I understand that DNA is represented a series of letters in patterns to structure the blueprints of DNA.

But how is actually “editing” and “submitting/deploying” code into living beings even a thing? Is it carefully done by hand through a machine?

Can you write the code out like a language? How is it even interpeted? How do people look and study at this code for example and say “these are the instructions for the wolve’s fur pattern” and it is strictly that, and not screwing up any other alterations?