One technique used by evangelists is to ask those who respond to their message to pray what is called the “Sinner’s Prayer”. The wording of this prayer varies; here is one version.
Dear Lord Jesus, I know that I am a sinner, and I ask for Your forgiveness. I believe You died for my sins and rose from the dead. I turn from my sins and invite You to come into my heart and life. I want to trust and follow You as my Lord and Savior. In Your Name.
This practice isn’t found in the Bible. There are several accounts of people believing the gospel and being saved but there is no record of any convert being asked to say this or any other prayer.