Believe
Jesus preached that we need to believe in something called "the Gospel," which comes from the greek term for “good news.” What is the good news? That God has provided a way, through the sacrifice of His Son, for our sins to be taken away from us so that we can have a right relationship with God. The Scriptures say,
“. . .‘Believe on the Lord Jesus [the Messsiah] and you shall be saved . . .” (Acts 16:31). No more, no less. Simply believe that through His perfect sacrifice, Jesus, God's Son, was able to pay the penalty for our sin.
If you want to trust in Yeshua as your Messiah, you can pray (talk to God) something like this:
Dear God, I know I have sinned against You. I believe that You provided Yeshua the Messiah as the blood atonement to cleanse me from my sins. I receive Him as my Messiah, and know that Yeshua has redeemed me according to Your Word. Thank You for forgiving my sins, removing the power of death, and giving me new and everlasting life as You promised.
It's not the prayer itself that saves you (the words above aren't a magic formula or anything like that); it's the heart behind the prayer that counts. Word it any way you wish. Just talk to God like you would talk to a good friend.
God promised that “. . . whoever calls on the name of the LORD shall be saved . . .” (Joel 2:32).*
*Joel 3:5 in Hebrew editions.
If you've made the choice to repent and believe in Jesus, your journey is only just beginning!