How to fit this part on?

[Spartan789]

Hi, the original drivers foot rest was detached when I bought this car and i'm not exactly sure how it fits on, there seems to be a screw cover of some sort missing but I don't know exactly what it's called or where to purchase it. I've attached a few images, thanks for any help.

http://imgur.com/xsiF5Og
http://imgur.com/kJcq708
http://imgur.com/nrksFsy
http://imgur.com/tflnG6W