How to Implement GeoFire in Ionic 4

Any ideas on how to implement Geofire on Ionic?
I followed this link:,

I install: npm install geofire firebase - save as the guide says, but I do not know if I have to import and declare in the app.module and how? Or if I also have to import and declare on the page that I’m going to use it?
Any ideas.

Thanks for help in advance