I try understand how http work's and can't understand on which level http protocol implemented, it's OS level, or it's depend from where I need use it protocol? For example if I want use it on C I must implement it on C language as library and only then use it?
http runs on top of tcp - tcp is implemented in the network stack of your OS. In terms of applications, http protocol will, I suppose, mostly be implemented in an application like a browser, but also command-line applications like curl and wget implement http. For languages such as Python there is a http server implementation in the standard library, or there are libraries such as requests which handle the client side of http so the python author just worries about the higher-level problem of which http requests to make. So the answer is, http is not implemented in the OS, it is implemented in applications. For your C application you will either have to implement http yourself (doesn't sound like fun to me but would be a good way of understanding http implementation, I suppose) or use a library if you can find one.