[Z-man]

iMessage allows you to SMS with other Apple products. Ex: if I send a msg on my iphone to someone else's iphone, it sends it via iMessage. The good part of that is: it doesn't cut into my cell phone provider's text messaging allowance for the month. iMessage also allows me to text from my non-cell enabled iPad to other Apple devices.

If iMessage is enabled, and you are sending /receiving an SMS from another iMessage equipped device, your sent message will have a light blue background. Sending a regular non-iMessage text will have a green background. iMessage only 'intercepts' messages sent to other Apple devices. Otherwise, the SMS is just a regular SMS. ALso - if your iPad is not 3G/4G enabled, you likely won't be able to send non-iMessage messages. So you may be having an issue trying to send a message via your ipad to a non-Apple device.

My suggestion: just turn iMessage on. it should link to your iTunes account automatically - ie: you don't need to register if you already have an Apple account, and if you are using the same account on your iphone and ipad.

Hope this helps,
-Z