What are some good sites for learning sign language?

I want to start teaching both of my children ASL. I know a little myself, but not much. I want to start with common words they use everyday mom, dad, sister, brother. Stuff like that. I figured the best way to do it, is every time I say the word do the sign, and try to get them to do the same thing. I know some people “make” up their own sign language for kids, just to help them better express themselves, and that’s fine. But I want to teach them real ASL. So was looking for a good site, any recommendations, and/or advice to get this started. Oh yea they are 2 and 4, so still young enough to learn it easily, I wish I would have started this sooner.
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