Check out MyFitnessPal to track what you eat, drink, and exercise. This will help you see where you're at and can help you get to where you want to be. It will also help you determine a starting point for the number of calories you should be eating daily based on your fitness goals. It can be downloaded to your smartphone, you can use the website, or you can do both.
As for workouts, start off at a slower pace so you're not over doing it right away and too sore to continue. There are all kinds of workouts on here that you can do at home or in the gym. I like how you can search based on time, intensity, location, and body parts.
Good luck and have fun with it! The more you enjoy something the more you're likely to stick it out.