Are all your pages full perhaps? you only get 11 pages and if these are all full, any new apps downloaded will not be visible until you free some space. You can create some folders by pressing an app until it begins to jiggle then press on the app and keep your finger on and slide it on top of another app and a folder will be created. You can rename the folder while still jiggling, just press the X on the Title line and then input the name you like.
If this isn't the problem, let us knowl
The IPad Forum is a community of members from all walks of life and from all over the world coming together to share our experiences and to help each other learn about this wonderful piece of technology the Ipad. There is a wealth of information already here in the many threads we have so doing some searches will answer most of the questions you have. If then you cannot find the answer you are seeking then by all means post your question. There are many friendly and informed members here only too willing to help you.
Well that is unusual, so the best step to do here is a Restart of our iPad
Press and hold the power off button, the one at the top right. You will see a slide appear to power off, slide this and the screen will go dark and a Whirly will appear. When the Whirly disappears your iPad is now off. Press the power button again until the Apple logo appears, this will take a few seconds and your iPad will restart. You should restart your iPad occasionally also as it will keep it running well. Now see if the FB app is there, if not a reset is the next step.
Hold the power off button and the home button simultaneously, keep holding them in and you will see the power off slide appear and disappear, wait until you see the Apple logo appear before releasing the buttons. It will take a little longer for your iPad to start.
Have a look for it, hopefully this has solved the problem, let us know.