I've never dealt with sending/receiving data from web servers in my games, so I absolutely have no idea how to do this. I tried googling for a good solution but couldn't find anything satisfying.
I currently get data from my web server by doing a HTTP request that gets the contents of a JSON text file stored on the server, and parses them in-game.
I do not know how to "write" high scores to the server, and even worse I do not know how to avoid people sending what they want to the server since the game is open source.
How is this usually done?