Have made some progress. I got the prototype/concept working now.
Step 1: A Arduino (with a ethernet shield) get’s the temperature from a Analog sensor (LM35D). Puts a username and password (for the web server) and temperature data together and tries to sends it to the web server.
Step 2: The web server splits up the data and send it to a MySQL database.
Step 3: A user goes to a webpage and see temperature.