how can i save the mapping of bones in skeleton to the Avatar to reuse that bones?

Hi all, as we know minimum 15 number of bones required to use model as human character in unity.
but with most of free downloaded model its not having that bones. I dont have knowledge to create own model in other modeling software. Please tell me how to solve this. In unity there is a concept to save bones and use it with other model How its happens. How to do it?

It’s a process called “rigging”, and you do it in 3D modelling software, not in Unity.

@tanoshimi thanks, i got it…