Adding phone contacts (phone number only) to a group

[nickgrahamfox]

How do I add phone contacts to a group and text them all simultaneously?

I am trying to make a group of contacts to organize a softball league. I have a verizon Moto G phone. I would like to add phone contacts (not google contacts, email address, etc...) to a group so I can text all players on the team at once. When I try to add members to the group in the "people app", the "phone" contacts are not available to be added to the group. Why? Please help.

Nick