Now, assuming your router is configured correctly with DHCP then you are up and running now. You don't need to enter anything else as it will automatically detect DNS settings, subnet mask and IP address etc.
To check its all working OK, press the little blue arrow next to your chosen network and choose "DHCP", it should list, either immediately or after a small delay, the values you router supplied it for IP, Subnet, Router and DNS.
Hint: A known problem is that if you tried to set things such as the IP and DNS manually then the iPhone will remember those settings and it will mean that unless you got them right your connection will still fail. The easiest solution is to start over by telling the iPhone to "forget" the connection you created. To forget the connection choose Wi-Fi and tap the blue chevron next to a network you've joined before. Then tap "Forget this Network.". Once your iPhone has "Forgotten" the old connection try again from the start.
** Despite the keyboard showing uppercase characters you can use upper and lower case characters. When the shift symbol is not lit its lower case, when it is its upper case. Be careful typing in the password as fat fingers can incorrectly type and Apple's auto correct will not help on password entry. I should know, I have fat fingers.