You're probably thinking of some words that the Apostle James wrote. He said, "Not many of you should become teachers, my brothers, for you know that we who teach will be judged with greater strictness" (James 3:1, ESV).
These are sobering words—but he didn't write them to discourage you or make you fearful. They simply are meant to make you stop and think about the importance of the Word of God, and to realize how serious a responsibility it is to teach it to others. After all, anyone who teaches the Bible isn't just dealing with an ordinary subject; they are handling the Word of God. They also are dealing with issues that affect the eternal destiny of those they teach.
The real question, however, is this: Is it God's will for you to accept this responsibility? Make this a matter of prayer, and be open to whatever God tells you to do. And if He does lead you to accept it, take it as a privilege and not a burden. In addition, make it your goal to be the best teacher you can possibly be "as you hold out the word of life" (Philippians 2:16).
Those young people will be facing some of the most important decisions of their lives in the next few years. They need Christ, and they need the guidance only God's Word can give them. The Bible says, "Let the word of Christ dwell in you richly as you teach ... with gratitude in your hearts to God" (Colossians 3:16).