Setting up a group on iPad

Unfortunately, you can't. That feature is lacking in the mail app on the iPad. There are third party email apps that allow you to create groups and to email to those groups, but the built in mail app will not do it.

You can create groups in iCloud.com in the contacts app, but you still can't email to those groups using the mail app.

Look at MailShot and Group Email with Attachments in the App Store.