Does the recipient have an iPhone? If so, just enable iMessage.
1. Go to iPad Settings by hitting the gears-turning icon. Scroll the left menu until you find "Messages". Tap that to bring up iMessage settings.
2. Flip the switch to "On". This will prompt you to log in with your Apple ID.
3. After you are logged in, you'll see your email in the "Receive At" area of settings. If you want to have email sent to a different address, you can adjust that by tapping on it and adding another email account (which you'll have to confirm).
4. You should now be able to send texts (SMS) to your friend's iPhone.
Hope this helps!