I accidently clicked forget this Wi-Fi connection on my iPhone?

I don't have Wi-Fi anymore, and I don't know how to get the password and stuff…
I have the AT&T Wi-Fi, with the little rectangular box thing. I know the name is 2WIRE___, but I don't know the password, where it is on the box, and it also askes for "security"… I don't know what that means? There's choices, for example there's; WEP, WPA, etc.

Unfortunately, once you tap that option on the phone there's no way to get it back without re-creating the Wi-Fi connection. I'm assuming since you said you have AT&T and the network is called "2WIRExxx" that you have U-verse? If memory serves, the Wi-Fi password was supposed to be on a sticker on the gateway box that serves as your "hub" for all the AT&T services.

If that's not the case, you'll probably have to give AT&T support a call to see if they can help you retrieve the passphrase and security type.