Is that the computer that you normally sync to ? With the iPad selected on the left-hand side of my computer's iTunes, the Apps tab on the right-hand side of iTunes is split into two sections, a list of apps which are on your computer's iTunes and a mock-up of the iPad's screen - because it's the computer that I sync to (and it therefore has all my apps and other content on), I can scroll up and down that list of apps and if I double-click on one of the apps it shows me where the app is on my iPad via the screen mock-up.
The usual ways to try and find an app on an iPad are to check all screens and app folders, use the iPad's spotlight search screen i.e. the screen before the first homescreen (there is a limit of 11 homescreens on the iPad after which apps can only be found via the spotlight search screen), check restrictions in case it's hidden, try a soft-reset to see if that then get it to appear, and to connect to your computer's iTunes and use the Apps tab to look for it.