Ado file for dominance command

Im trying to run the following command in stata 15

dominance y [aw=weight], sortvar (x) rule both

but it says dominance command is unrecognised. after reading couple of forums i came to know that i have to download its ado file and then install the command. Despite multiple attempts, im unable to run this. Kindly help me with the following queries

1. how and from where to download ado file to run dominance command for stata 15
2. how to go about installing it.

Any prompt reply would be greatly appreciated