Most likely:
* HRING-oh (with the "h" pronounced, similar to "ring" but with a longer "i" sound)
Other possibilities:
* HIN-gro (emphasizing the "i" and sounding like "hin" followed by "gro")
* HREEN-go (with the "g" sounding like "j" and the "o" sounding like "oh")
It's best to ask the person with the name how they prefer to pronounce it.