Brining the turkey?

[crash]

What's the purpose of doing so?

Brining poultry is done for the same reason as adding salt, or seasoning, to any food; it enhances the natural flavour of the meat. The added bonus with turkey is it keeps the flesh moist.

You can brine with water and salt, I do a chicken with beer and salt, there are thousands of brine recipes. With a turkey you'll probably want to add some sweetness, like a cup of sugar or something like honey or maple syrup. Herbs and garlic also work well. As does a little chilli etc. Go google..