well start off with dropping the fast food...eat healthy foods and drink lots of water. cut the sodas completely. Start doing brisk walks after you get up from your sleep. Do this before you eat your first meal of your day. Take a good multi-vitamin and a multi-mineral. You can add extra vitamin c and vitamin e also.
Try to eat atleast 5-7 small, balanced, healthy meals each day. This will help to boost your metabolism and help to loose bodyfat.
Start off with that first and see how it goes