A background check company is a good place to start...
Locate the state, then the city or county where you think they are being held.
There are hundreds of online services that provide criminal background checks, some better than others. This is a trusted and reliable service for finding information on people.
To find out how to visit someone you know, begin your search for an inmate or arrestee here:
To find your jail or prison visitation policies, begin by finding the facility or prison system here: