If you don't have equipment at home to exercise, then you NEED to join a gym. You don't need to lift weights for muscle. Using the elliptical trainer, treadmill and bicycle will help you lose weight. If you don't want to join a gym and is able to go running outside, then I would suggest you do that. Running will for sure help you lose weight and tone your body fast.
I would recommend you exercise daily or 4-5 times a week for 1 hour (Very good results). If this is too much for you, then aim fro 4-5 times a week for 30 minutes and then increase that to an hour.
Make sure you eat 3 meals a day, and 2 snacks in between. Breakfast can be anything like cereal with fruit and yogurt or egg with toast and fruit. Lunch can be a sandwich with protein such as a turkey sandwich or a tuna sandwich. Dinner can be anything like fish or chicken with veggies. Snacks can be things like a small amount of nuts or yogurt or fruit and veggies.
Aim for 1200-1500 calories a day (NOT less than 1200) and if you're planning on exercising a lot, make sure you have enough calories like 1500 or 1600 a day because you will be burning lots of calories.
Drink 8 glasses of cold water daily and that's it :D Good luck!