Advice.....
Core work is always good, for many, many reasons, but not necessarily for "toning", unless your body fat is low enough that the muscles show! I'd suggest whole body resistance exercises a couple of days a week, and cardio another couple days. There's lots and lots of great information and routines out there on the 'net to get you started, whether at home, or in a gym. You might want to check this out:
www.ehow.com/how_2039669_start-resistance-training-routine.h tml
www.ehow.com/how_2039669_start-resistance-training-routine.h tml