what does digital currency transfer look like "code" wise?

I'm curious as to what goes on in the background, what methods of encryption are used and what the code looks like DE-decrypted to make this happen. How can i give some one paper dollar and send it to my prepaid card and my moneys on there and then i can withdrawal my dollar back out Some one please explain this.

If this is in the incorrect category please direct me to proper one please thank you..