1). The Introductory Call to Praise (1-3).
This is a call to make a loud noise so that all may know that they are praising YHWH and giving Him thanks, using every means at their command.
‘Sing aloud in YHWH, O you righteous,
Praise is comely for the upright.'
Give thanks to YHWH with the harp,
Sing praises to him with the psaltery of ten strings.
Sing to him a new song,
Play skilfully with a loud noise.'
Once again it is the righteous and upright who are called on to give praise and thanks to YHWH, and to sing aloud and make a loud noise. Indeed for the upright it is ‘comely' (seemly, beautiful) to do so. He is to be praised in every way possible. There can be no true participation in His worship by those who are not upright and righteous, at least in intent. Man looks at the outward appearance, but God looks at the heart.
Note the musical instruments that are called into play, the harp and the ten-stringed guitar. They are to use them without restraint in His praise. And they are to sing a new song, compare Revelation 5:9; Revelation 14:3, because He is continually doing new things for them.. Indeed the idea that the people of God should continually be creating new songs in response to His new mercies is common in Scripture. See Psalms 40:3; Psalms 96:1; Psalms 98:1; Psalms 149:1; Isaiah 42:10.