Plumeria Help!

We got a few plumeria plants from a women free of charge and she also gave this little one here. I have no experience with these kinds of plants but would also love to keep it alive and well. I could really use help on how to promote root growth more than anything. We just got these so I have just kept it to the side but I’m afraid to stick it in water like some other plants because I really don’t want it dying or getting mushy. I have kept it inside since we have only had it for 1 day so no much sun has got to it yet on our end.

We got a few plumeria plants from a women free of charge and she also gave this little one here. I have no experience with these kinds of plants but would also love to keep it alive and well. I could really use help on how to promote root growth more than anything. We just got these so I have just kept it to the side but I’m afraid to stick it in water like some other plants because I really don’t want it dying or getting mushy. I have kept it inside since we have only had it for 1 day so no much sun has got to it yet on our end.