whirlpool bath

we are installing a new jacuzzi whirlpool tub to our masterbath. It talks about a tile flange kit, what is this? We plan on tiling around the tub and walls. this is our first tile job. Is this flange kit something we buy, or make?

does it need to be installed, my husband is very handy and we have done all the remodeling in our home built in the 40's.

I read over the complete installation and can't find anything that explains what this is, except that it is a kit needed to install the tub the way we would like.

Please Help.