You aren’t dumb at all. Everybody learns by trying his/her best.
You need to solve the challenge from the client-side, but it is usefully to download the sources and see what goes on the server-side when you try out different things as a regular user. :)
Yes, it requires, but if I tell you the technique, it will kill the fun part.
You should play in your downloaded environment, then search with Google based on what you have found.
Do not give up! You will complete the level! :)