Contact name is red when sending message

Do you mean that, when you start typing a contact name, and it appears in the drop down, it's in red? If so, that would indicate that the person does not have iMessage and that you do not have an iPhone connected to your iPad to allow it to message non-iMessage devices. If you have an iPhone, you can link it to your iPad by going to Settings>Messages>Text Message Forwarding and selecting your iPad.

If you see a red exclamation point

If you try to send a message and you see with an alert saying Not Delivered, follow these steps:

1. Tap , then tap Try Again.
2. If you still can’t send the message, tap , then tap Send as Text Message. Messaging rates might apply. Contact your carrier for more information.