One of the main things Jesus did during his earthly mission was heal people. He also taught the people things they needed to learn about God and God’s ways.
He did other things as well. He fed a multitude, he blessed children, and he did a miracle at a wedding.
He finally died on the cross to redeem mankind.
But as many as received him, he gave them power to be made the sons of God, to them that believe in his name. John 1:12 Douay-Rheims
If you declare with your mouth, Jesus is Lord, and believe in your heart that God raised him from the dead, you will be saved. For it is with your heart that you believe and are justified, and it is with your mouth that you profess your faith and are saved. Romans 9:9, 10 NIV
Jesus did a complete redemptive work. Healing is a part of the redemptive work of Christ.
But he was pierced for our transgressions, he was crushed for our iniquities; the punishment that brought us peace was on him,and by his wounds we are healed. Isaiah 53:5 NIV
The way to build faith is to listen to the promises of the Bible. Listen to them read by someone else or read them yourself. Faith is a substance that grows when we hear the scriptures, the Word of God, the Bible. People develop faith and learn to receive healing from the Lord.