How to connect to Wi-Fi on an iPhone 4s

So I recently upgraded to an iPhone 4s and when I got home to connect it to Wi-Fi it kept saying my password was incorrect, so I went back, and then when I went forward again, it didn't ask for the password. Now when I try to connect it from Settings, it doesn't even ask for the password, it just refuses to connect and I'm using up my data. How do I get it to connect!

You need to delete the saved password for the network or at least edit before connecting and you can do this by going to Settings, General, Network then Wi-Fi and click the right arrow icon next to the network connected and select, forget this network. After this you will be able to start again and be prompted to enter a new password.