How do OT rules work in ranked matches?

[XxCavaliers360]

My opponent quit before I was able to find out. He scored a field goal with about 45 seconds left, I did a couple plays and called my timeouts and then paused the game to look up the rules and he quit out. There was like 30 seconds left; did I have to score a field goal by the end of the period or would it carry over into a second overtime until I scored or turned it over? I know I have to score a TD to win or a FG for sudden death (I'm assuming), but the time is confusing me.

I guess this applies to the NFL in general, though Madden's OT's are half the length?

And the recommended plays did not at all infer that I should be rushing. I found this which says the game would end (in my case 23-26), but it would continue into a second period if it were a post-season game.