A speech into sign language

Hi, i want to make an app for deaf people and i want it to be like this, there a image of a hand or avatar(and if anyone can tell me how to get an avatar of hand can move i will be thanks)and when the app receive an voice of someone in to convert it into sign language like this when someone say something like: "Hi", the avatar or image move and make the signs that say Hi anyone understood me please help and i will be thanks.
Thanks

You will need a database of images/animations and words

You're not the first:

https://community.appinventor.mit.edu/search?expanded=true&q=sign%20language

Can you explain more what i should to do and how

Thanks