Problem with front brake pads

[dukey28]

Hi I have just bought a stomp hustler pit bike and to get it into my car iI had to take the front wheel off. When I got home I put the front wheel back on but noticed that one of the brake pads he fell out of the caliper. I found the pad in the boot of my car, it was the smallest pad that had fell out. So I removed the wheel and the caliper but there is no where for the pad to fit the gap is tiny I can see that the pad somehow butted up to the silver cylinder looking thing on the caliper but that is all the way out and touching the other pad. While the wheel was removed and the pad was missing my partner pressed the front brake leaver a few times, could this have caused it. As I'm new to this I have no clue what to do. I've seen a tutorial on this forum but the caliper and pads are different. What do I do?

Much appreciated