case fan help

[Gbuzz]

Just want to install a new case fan to cool down my computer, but there is only a rack on the case, seems like I need to get a screwless fan on it?
Anyone haas idea where I can such a fan and how can I install it?

 

[serialb]

Most case back panels have holes on it. What I usually do is to use cable ties to tie the fan to those holes.