adopted sister – deaf – sign language?

my mum & dad have just adopted a little girl called bailey..shes 6
she is almost completely deaf…when someone SHOUTS it comes out as a really really quiet whisper and she can hardly hear that
so talking and whispering she cant hear
she knows sign language..
how can i learn sign language quickly & easily so i can talk to her
i havnt got time to go to a special teaching place
iv got my internet & thts the most i can use
help please
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