You see, singing for God isn't about the key, pitch or rhythm, it is about the attitude. The Lord deserves our worship and our praise. In everything we do, we should lift the glory to Him. God created you and it does not bother Him if your voice doesn't sound like the angels, He wants to hear the song of your heart. He wants to hear you say how much you love him.
Don't get too caught up on words like hymns or psalms. It all means on thing - worship the Lord your God with all your heart, all your soul and all your strength. Give everything you are to Him because He gave you everything you are. You are not lacking because He made you whole. by living in His strength, not your own, there is no obstacle, no challenge and no victory you cannot rise to and overcome. Even our prayers are like music to the Lord our God. Sing songs to the Lord and give Him all of yourself. Tell God how much you love Him.