Each year in the first or second weekend of December, Disneyland holds the Candlelight Processional where hundreds of chorus, orchestra, and chime members perform music to accompany a speaker as he or she tells the Christmas Story (usually a celebrity).
Disneyland sets up risers on Main Street, in front of the Main Street Train Station, with seats set up at the Town Square area, facing the train station. As you can imagine, the space isn't really big, so there are not really that many seats.
Shows are twice a day, usually 5 or 5:30 & 8pm, on Saturday & Sunday, only.
As said, if you can get a dining package, you can have a meal at one of the selected restaurants (there were 3 price tiers, depending on the restaurant, and all a bit pricey), and then have a reserved seat.
If you opt not to get a reserved seat, you can still see the Candlelight Processional (CP) by getting there early & saving a spot.
If I remember correctly, cast members start someplace (could be the gate @ It's a Small World), and holding candles, process to the risers, singing hymns along the way.
When I saw it (back in 2001) the risers were set in a way so that when they stood on them the cast members resembled a Christmas tree.
I remember being impressed when I saw it, and it is very well done.