How are files stored in memory and how can i use that knowledge in C++?

How are files stored in memory? I suppose that when i write in a text file something like Hello World, the file in memory looks like this: 01001000 01100101 01101100 01101100 01101111 1 Byte 1 Char?

Well... I'm 90% sure I'm wrong about this and that's why I put this question.

The actual thing is that I really want to know how Images are stored into memory because I want to use this to edit images or create ASCII art, and i feel like i could do this without a 3rd party library.

The reason I didn't put my time into learning a library is that there are lots of them(I don't know which one to pick) and i don't know at what point I should looking into them... Well, this would be a different question