Q: How can I send a iMessage on my iPad

iMessage is part of the Messages instant messenger app that is pre-installed on all iPads and Macs. Any message sent between iOS devices and Macs will automatically be sent as iMessages. If you are using Messages on an iPhone, then you can send iMessages to other iOS/Mac users and SMS/texts to non iOS users. You can refer to the left nk below to make sure that you have iMessages activated in your settings. Best of luck.

Use Messages with your iPhone, iPad, or iPod touch - Apple Support