Boston is a relatively accessible city, with many options for getting around (here's a good guide, if you are interested: Visting Boston ). Jamaica Plain is located south of the city center. See the map showing Jamaica Plain below.
We often take the subway, called the T, to get around. Jamaica Plain is accessible from the Orange Line. The closest stop to both our apartment and the wedding venue is Green Street Station, which is marked by the little circle on the map below. The large circle shows the city center.
Another option is to either take a cab or use an app-based rideshare service, such as Lyft. These are plentiful in Boston; we've never had a difficult time finding a ride.