Hello
New to bonsai and I need some help.

A friend dug up a California juniper in his back yard the other day
and brought it to me in a bucket filled with sand and potting soil.

I hosed it down and now I am unsure what to do.
I would like to ensure the survival of the tree.
It didn't have many roots other thanthe large one that was severed.
I do have some of that root hormone.. should I put that on it?
should I keep it in a pot?
bury it in some cactus mix soil?

Can someone give me some tips on how to keep the plant alive?
Thanks for your help

William