Cant Send A Message iMessage Mac

Hi so I recently got my new MacBook Pro and I can't seem to message someone when I put their phone number in the section where it says To: the number just shows red and I am trying to text my dad who unfortunately has a android and I have to do it via sms I think. How do I do this I am a Mac newbie or is it that you can't use sms on Mac. as you see here the number is red

and it doesn't let you send a message at all when you put in the field and press the return key