Advice for building on property

[Adam Tamayo]

My wife owns an acre of property in they Heyburn Idaho area. The property was handed down to my wife's siblings after her dad passed away. My wife's siblings have built 2 house on this land as there own houses they are living in 

The property is a total of 15 acre and each siblings got a portion of the property. My wife and I are looking into building a duplex on it.

since I am still learning on investing in real estate. My question is, what's the best approach on getting this going.