For example, if a player joined a game with a GUI to input information, how would that player submit the information and allow me to view it in-game or even be sent somewhere else using HttpService?
Please can you explain how I can do this and if I were to use HttpService to send information to a website, do you suggest any? (Like Trello?)

4 comments
are you trying to make a phishing game
No, I'm not that desperate.
You would want to make a post request to the Trello board. If you do not know how to utilize the Trello API well, there is a module script on ROBLOX that will allow you to make those post requests. You will need to get a token so the script will have permission to post as you.
This tutorial might be a good starting point: http://wiki.roblox.com/index.php?title=Sending_HTTP_requests