How do I put on the whole armor of God? Pray. You can pray something similar to this prayer:
Lord of the universe and Source of all spiritual power: I come to You to prepare for spiritual battle.
Armor of God: Belt of Truth
Please give me the Belt of Truth that I might stand against the father of lies, the devil. Jesus is the Truth and I choose Him to give me eyes to see life through His sense of reality.
Armor of God: Breastplate of Righteousness
Please help me to put on the Breastplate of Righteousness. Jesus is my Righteousness. I have none of my own. I am ready at any time to deliver the message of the Messiah Who died so the world may live.
Armor of God: Shield of Faith
I trust You to shield me from doubts and deception, for it is by faith that You saved me.
Armor of God: Helmet of Salvation
Protect my mind through the Helmet of Salvation. Remind me that I belong to You.
Weapon (Melee) of God: Sword of the Spirit
Teach me how to use the Sword of the Spirit–the spoken Word of God–to defeat my Enemy, the devil. Help me to defeat him just like the Warrior of all warriors (Jesus Christ) did.
Weapon (Long-Range) of God: Prayer
I pray for all this in the strong Name of Jesus, the One Who is seated in the heavenly realms at the right Hand of the Father. The One Who has reserved a place for me at His table. He is the One Who deserves the credit and the glory always. Amen.