Hi! That's a great question. This was 6 years ago and as far as I can remember you couldn't really customize your GitHub profile that much, at the time.
I had a few small websites. Prior to the interview, I looked through the code to make sure it looked nice and tidy and tried to make it look as professional as possible.
Reading code written by more experienced people is a good way to see how clean code can be written. That's how I learned.