I'll just try to answer this in the simplest way I can think of.
To make your own banner and ikon just use editing programs such as Photoshop, PhotoScape atau Gimp atau any other that could help but anda probably already knew this.
To muat naik a new ikon and banner for the spot, just go to the spot anda made and follow the instructions that
link gives you. I hope this helps! :D
I also hope I explained how to do this well, just please let me know if I didn't.