My map (Mapbox) takes up the whole background of the site so the center is in the middle of the site. But the focus of the map for the user is on the right side because I have
First you will need to know the lat and long of the point on the map you want to center on. Then it is simple, just call Map.map.setView passing in your coordinates and zoom level. Api reference: http://leafletjs.com/reference.html#map-set-methods
If you don't know your coordinates then you can find it by trial and error, just create a marker and add it to the map.