My new iPhone 5s keeps on saying that my phone isn't backed up?

What does this mean and how can I fix it. Oh btw here's quote on quote what it says

"this iPhone hasn't been backed up in 3 weeks. Back ups happen when this iPhone is plugged in, locked, and connected to Wi-Fi."

Umm… It means what it says. You apparently haven't backed up your phone. We either use iTunes to back up/sync our iPhones or back up all content (apps, contacts, etc.) on iCloud.