Ooooo - a big topic!
I would recommend Mike Brewer's 'Kick-Start Your Choir' and his book of Warm-ups (both pub by Faber) to give you some general ideas of how to start.
A really excellent book is Peter Hunt's 'Voiceworks' pub bu OUP. It's expensive (about £45) but includes a CD and lots of photocopiable pages. It has ideas for warm-ups, how to teach a song, how to perform the piece and so on.
The Sing for Pleasure Junior Song Books are wonderful. I think you can buy the set of 10 for around £25 and they contain masses of material - action songs, simple rounds and part-songs. More info on their website I think.
I also use a lot of Alan Simmons books and Doreen Rao's Choral Music Experience (in particular the first Junior Anthology).
Alfred Choral Publishing do excellent very simple part-songs.
Also anything by Lin Marsh or Jan Holdstock goes down very well.
Good luck! Choir training is pretty exhausting but VERY rewarding!
(Oh - btw - the word is INexperienced....

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