system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does DNA even do things?

I get the basics, I think. DNA is made of four thingies, it codes for proteins that are important (?) And it determines what traits you have. And then it splits in half and replicates itself to form new cells. At least that's my understanding after a couple days of biology class and about an hour of google.  Still not quite sure how DNA even tells the cell what to do, but I sorta have an idea of that.

What I really don't understand and can't seem to find an answer to, is how does DNA work? As in, if there are only the four nucleotides, and they match up with each other in a certain way, then all the instructions must have to do with the order of the nucleotides, right? So how does a bunch of nucleotides in a certain order determine what your cells (protein thingies in the cell i guess) are supposed to do? What makes one order different from another? 



Unless I'm completely wrong and the order isn't even important.
gpt
Short answer: structure = function.

The order of the four "thingies" in DNA determine the order of the joined-up LEGO blocks that we call a protein. DNA uses 20 different, specific LEGO blocks. For example, AAA codes for one type of LEGO, AGA codes for a different one, and so on. (There is overlap - each of the 20 LEGOs has several different patterns that code for it.)

Due to the basics of physics and chemistry, each of those LEGO blocks acts in a unique way with respect to the other LEGO blocks around it. Certain parts of LEGO A attract and repel different parts of LEGO B, and ditto for C, D, E, and F. So at the end of the day, you've got this long string of LEGOs that folds into a certain specific shape, and that determines what the finished protein actually "does." Proteins are kinda like very simple machines, and the order of their parts determines how that machine will behave, simply due to the rules of chemistry.