Find Evensong near you, today.
There are various musical items in a Choral Evensong service. These are, typically:
Introit (sometimes); Preces; Psalm; Magnificat; Nunc Dimittis; Responses; Anthem; Hymn(s); Organ Voluntary.
The links below (highlighted in red) demonstrate some of the greatest manifestations of these musical forms.
And here is a Gramophone article listing some choice recordings of the Choral Evensong repertoire - by Michael White
In basic terms, if there is an introit, this is the first thing that is sung by the choir, and nowadays can take various forms, most usually a hymn or a metrical psalm.
These are short petitions that are sung alternately as versicle (by the precentor) and response (by the choir, and sometimes congregation). This form of prayer is one of the oldest in Christianity, finding its source in the pre-Christian Hebrew prayers of the Psalms in Temple Worship. The 'Preces' and 'Responses' are separated within the Evensong service, with the Psalm, Magnificat and Nunc Dimittis happening in between them (see order of service above).
Particularly recommended are Smith, Leighton, Shephard and Williams. But if you can't find those, try these:
The Old Testament Judaic book of 150 songs of praise, lamentation and thanksgiving - many of which are linked to King David.
Magnificat: This is the joyful song of praise by the young woman, Mary, rejoicing at the prospect of the birth of her child, Jesus.
Nunc Dimittis: This is the song of an old man, Simeon, praying to God to let him depart in peace now his life has been fulfilled by meeting Jesus.
Particularly recommended are Byrd's Second Service; Stanford in G; Howell's St Paul's Service; Leighton's Second Service; Holst's Nunc Dimittis and Sheppard's Second Service. If you can't find them, you could trying listening to these:
This is a choral composition set either to a text from the Bible, or another religious text. Often in practice, the material for anthems and introits are interchangeable.