Teaching small kid chess

get a big stick ?

Seriously, I don't think we can teach a child (or that we should even teach a child) how to play chess unless the child wants to learn.  Chess, after all, is a specific board game; and not everyone likes every kind of board game.  If your 12 year old wants to learn chess (and assuming he/she is a normal on the developmental spectrum), then I think just giving him a beginner's chess book is all that is needed.

Yeah she is interested and they want me to her in chess...

The game No Stress Chess was fantastic for teaching my kids. They graduated into "real" chess extremely quickly, but I think that just shows the value of No Stress Chess

Start simple, don't push them.

Teach the basic general chess opening principles. Teach elementary endgame mates like two rooks against a lone king mate, king and rook against a lone king mate and finally queen and king against a lone king mate. Show the tactical themes like pin,fork,skewer, discovery etc. After showing them different tactical themes, give them puzzles everyday. Maybe 3 puzzles everyday is enough. Let her join a chess tournament. If there are opponents that she can play, encourage her to play against them. 

You will find this link useful for teaching basic tactics and mate.

http://www.chessfornovices.com/whatarechesstactics.html

http://www.chessfornovices.com/understandingcheckmateinchess.html

I'm trying to teaching my sister that she is 3 years old...

For lots of chess pedagogy insights, like www.facebook.com/premierchess. 

For a real beginner, my view is that you play "with" them (against a computer, for example) instead of "against" them.  Explain why you might prefer some moves to others (i.e. this move helps get pieces out, that move forks this piece, etc), have them suggest moves, and discuss.   

Kids learn quickly via emulation, and you're teaching them to emulate you.  

What do you mean by: "no stress chess"?

Search "No Stress Chess" on Amazon. It is $16. Basically, it is a chess board and a stack of cards. Each player selects a card. Each card shows one piece, names it and shows a picture of how it moves. The player then is required to move that piece. 

It removes the stress of the game by limiting your choices and reminding you how the piece moves. After a few games you can make it harder by selecting three cards and then the beginner has to choose the best move out of their five possible moves.

From there, it is a short step to "real" chess.

A great way to teach kids starting out is with chess kid. It doesn't rush while teaching and it grades kids before moving on to the next fundamental. One on one coaching is always fantastic but the internet has more than enough resources  

Just use the chess lessons!

Introduce the game, the basics. Play a few games to see if they like it, then go from there if they show any interest. There are several books for child beginners.

I’m only nine and I beat some adults

try to stick them with an interest to the game, may be start not from rules..  a story or why do people play chess