Saying a memorized prayer like the Lord's Prayer isn't wrong, as long as we don't lose sight of its meaning. But yes there is more to praying than this, and I hope you will learn what it means to pray more freely.
Have you ever stopped to think what prayer really is? Prayer is simply talking with God and God wants us to talk with Him. You see, God is our Heavenly Father, and when we give our lives to Jesus Christ, we are adopted into His family and become His children forever. The Bible says, "To all who received him, to those who believed in his name, he gave the right to become children of God" (John 1:12). Have you received Christ into your heart? If not, turn to Him and ask Him to come into your life.
What does this have to do with prayer? Simply this: Think back to your own childhood for a moment. When you were young, did you talk with your father in a series of carefully memorized sentences? No, of course not. You talked with him freely and openly about everything and he delighted in that.
The same is true with God, your Heavenly Father. He delights in the prayers of His people! Don't worry whether you're eloquent enough; your father didn't turn you away when you spoke baby talk and neither does God. The Bible says, "Let us then approach the throne of grace with confidence, so that we may receive mercy and find grace to help us in our time of need" (Hebrews 4:16).