I can't find my Twitter app I downloaded on my iPhone?

I downloaded the Twitter app onto my iPhone, and the app icon isn't showing up. I just bought the iPhone today, so there aren't a lot of other apps downloaded. Also, when I go to search and type in "twitter," it doesn't come up. It just says, "search web," and "search wikipedia." When I go back to Twitter in the app store, it says that it's installed. I went to my settings and it also shows Twitter in my settings, but the icon is nowhere to be found.

First check at settings app then go to to general then spotlight search (if it on ios 5) or homebutton and check if all the words are checked if they do well reboot your iphone if not check it and then do it again