How are alphabetic characters programmed into a computer? I'm no cs student, I'm a programmer. I have a couple of questions and a few assumptions that I will make here (correct me if I'm wrong please).

From my understanding is that all the sequences of 1 and 0's that computers execute are just representations of actual data or instructions that tell other hardware on a system what to do like telling a graphic card to change a pixels color on the monitor.

01100001 being the representation of the letter "a" and that this sequence of bits has been chosen by the fathers of computing/ascii or what have you to represent that letter, it could just as well have been some other sequence right?

All computer systems have agreed that those bits mean the letter "a" for all of the computers around the globe to be interoperable, if there were no standards in place for this the internet would be a mess.

What I want to know is: where is the information stored on a computer that tells it that these sequences of bits here mean/represent the character "a"? Is it in the OS or directly on the motherboard or am I just completely wrong?
It isn't stored anywhere. 01100001 could represent anything. It could be the ASCII character "a" or it could be the integer 97 or it could even be something different entirely. It's up to the programmer to tell the computer what to do with 01100001, for instance by supplying a font file that tells it how to map binary sequences to the instructions to draw a character on the screen. Often this is taken care of in libraries but the OS and motherboard have no idea that 01100001 represents "a".