Board Game Arena

I grew up playing canasta, so I know how to play canasta. But none of the links provided here tells you how to play hand and foot. For example, they say you deal a 'foot' which you can't look at, but no place does it ever mention the foot again. Do the cards just sit there out of play? Or do you use them for something at some point? The rules also say 'Sometimes you deal 11 and sometimes 13' but don't elaborate. It's quite a mess.

I would be happy to teach you. There are basic rules, but many variations to which one has to adapt.The strategy tips used to tell one HOW to play, but someone felt that the strategy tips should be just that and decided to delete such. True diehard hand and foot folks are kind and inviting, and enjoy bringing others into our H&F world.

Quick and dirty answer. When you get rid of the last card in your hand, you then pick up your foot and play it as your new hand. You are basically dealing yourself 2 hands to play.
If you discard the last card in your hand, you play your foot the next play.
If you place the last card in your hand on a meld, you get your foot and immediately begin playing it.
The rest is very much like Canasta. Clean melds, dirty melds, wild melds, completed melds/books/canastas.
There are good tutorials if you want to go through one. I think if you play Canasta, it will likely clear up your questions.

There's a video on this page literally next to your post on my screen.
Do you not see it?

You can just tell people you are a newbie and see if they'll be nice and help.
Just don't play an arena game until you know a bit about what you're doing or you'll be eaten alive!

https://www.youtube.com/watch?v=owuxotiNjI4&t=245s

If you look at the Rules summary on the Hand and Foot page and scroll down to Order of play, it explains a bit more about your foot.

HTH