How to text to an iPod
To receive messages on your iPod, as long as the other person is using a device which is iMessage capable, they will be able to send you texts via iMessage.

To set up iMessage:


On device, go to Settings -> Messages
Turn on iMessage
Once set up, make sure you choose your email address as one that can receive iMessages (tied to your Apple ID)
Have friend send messages to you via iMessage as they would a normal text to one of the addresses provided in iMessage setup


More information can be found here and here