Salvation is personal. It requires a response.
"If you confess with your mouth the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved.
— Romans 10:9
God has done everything needed for your salvation. But He won't force it on you. It's an invitation — and it requires your response.
There is no "magic prayer," but you can express your faith like this:
"Lord Jesus, I know I am a sinner. I believe You died for me and rose again. I turn from my sin and place my trust in You. Forgive me, save me, and be the Lord of my life. Amen."
If you prayed this prayer and meant it from your heart, welcome to the family of God.