Hi and welcome to the Forum!
I have an iPhone 3GS and the iPad 2 also. I have my phone set up to receive messages on both my number and email address and my iPad is just the email address. Have a look at your settings in your iPad, Settings - Messages, make sure iMessage is turned on here and that you have your email address in the Receive At tab.
Now look in the Notifications tab then Messages, turn it on here and set up your alerts. On your phone do the same thing but put both your number and email address in the Received At tab, also check your notifications are on here also. If you send a message to each other from the iPad, you should receive this message on both your phone and iPad as it is using your email address rather than your number.
Do all these steps and let me know how you go.
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.
We also have our own App - It is a very simple app to navigate.
http://itunes.apple.com/us/app/discussion-forum-for-ipad/id412896524?mt=8
Reading the IPad manual is a great place to start so please download a copy of these.
http://www.support.apple.com/manuals/ipad/
2 very informative threads from which you will learn many tips and shortcuts for the IPad.
http://www.ipadforums.net/ipad-general-discussions/21590-tips-tricks-those-us-who-dont-know.html
http://www.ipadforums.net/ipad-os/49581-ios5-tips-tricks.html
We have rules like any Community so please read these also
http://www.ipadforums.net/forum-rul...um-rules-everybody-please-read.html#post14697
Once again we welcome you here and are so pleased you have joined us!
Sent from my iPad using iPF