There's lots of free advice online about portion sizes.
Basically I aim for as unprocessed/fresh as possible. As much vege as I can manage and lots of water.
Calorie King and MyFitnessPal are free online recording tools. Personally I find recording my intake the best way as I feel more accountable. They also offer meal plans if you want.
There's also lots of free online home workouts. Basically though walking is a good start.