Mac Messages app shows phone numbers instead of contact names

Hey guys! I recently purchased a Mac Neo. I set it up with my iPhone and everything and it shows that everything is synced. Well, when I open Messages off my Mac, I see all my conversations with everyone, but the issue is that I only see their phone numbers as their names. I can only tell who I am texting based off my previous messages with each person. How do I fix this issue? I would appreciate any sort of tips from you guys!