Roulette is probably one of the simplest to play. A ball in a wheel goes around and will land on a single number, but that single number will be in multiple defining groups.
For an example, say it lands on 28, 28 is inside a red box and is part of the 3rd 12, so therefore if you bet 28, red or 3rd 12, you'd get money back and extra for a right guess.
There are also other things you can bet on, like evens, odds, a certain row, 1st 2nd or 3rd 12 numbers, etc...
If you want to be safe, colours are one of the safest things to bet on, though again they usually lead to the least profits, whilst 0 and 00 are extremely risky bets but get you amazing profits.
Personally haven't heard of craps until now, so I can't tell you anything about that.
Poker can be pretty complex to explain and I'm not sure I'd do good at it. Basic theme is you've gotta get the best hand you can, based off of the 2 cards in your hand and the cards in the middle. They start off showing 3 cards, then 1 more, and then the final card is shown.
There are 4 actions you can do:
Check - Essentially a "pass to the next player" command. If everyone does this it goes onto the next round. Only available if no one has raised.
Call - Match the bet of the last player. Check is not available if you have the option to call. If everyone does this it goes to the next round.
Raise - Raise the bet from the previous one, not sure if this is true but I believe a raise starts at 10 and keeps going up as people raise. If people keep doing this, the round will keep going until someone raises and the rest of the player call or fold.
Fold - Simplest action, basically just a surrender. I don't recommend it if no one is betting anything, you have a good hand or you're in the last round. Use it for if the bets are getting too high or you are looking to have a horrible hand.
Hopefully this might help with teaching you about hands, because I'm gonna be honest, I don't know too much about them myself.
"NintenDON'T sue me please haha"
Basic casino games. Poker, craps, roulette. Poker (especially Texas Hold'em) has a lot of layers. Craps and roulette, I can't even understand what's going on on the table, much less make a reasonable bet.