Easiest way, use gene scanner to locate. You will have to kill it and it will drop an altar, which you can place.

Once the altar is placed at night you will be able to make an offering (which will be creature tributes on the map you are on)

Then you summon it and have to kill it. Repeat this process, for higher levels you will need to do this multiple times. Failure to offer the tribute in time will cause it to spawn alongside the creature relating to what was requested. For example if a Giga heart is required, failure will spawn a Giga. 3+ failures and the altar will be destroyed. One you have completed the ritual, it will spawn tamed. Good luck!