There is some info about FaceTime, including troubleshooting, on this page : http://support.apple.com/kb/HT4319

These two links may be of help:

iOS: Using FaceTime

iOS: Troubleshooting FaceTime

Go OZ! I just spent two years there and I love it!

to use facetime you need an appleid:

without a credit card: http://support.apple.com/kb/ht2534

with a credit card: http://support.apple.com/kb/ht2731

(facetime is free by the way, it's just two different ways to create the appleid)

once you've got that, go on your iPad to settings>Facetime and enter the appleid and password there

after that you'll be able to facetime other people via their appleid using an apple product (iPad, iPod, iPhone, Mac), if:

-they already have facetime setup

-they are available

Good luck

iOS: Using FaceTime

iOS: Troubleshooting FaceTime

iPad: How to Make a FaceTime Call

iPad 3 Users Manual ( Go to Page 55 & 56 )

Open FaceTime, go to Help menu and click on FaceTime help, go through ALL links in this.

FaceTime for Mac: About HD video calling

These are ALL of the links to "basic" info on how to set up and use FaceTime, if you are still un able to set FaceTime up AFTER you have read ALL of the info in these links, you may need to have a friend help you.

iMessage and Facetime are usually connected and when one doesn't work, then other one is the same.

But it is weird if you can connect to apple store with the same appleid.

check on appleid.apple.com and manage your account to see if the appleid is verified.

otherwise try a reset on the ipad: press and hold home button + sleep/wake button untill you see the apple logo.