One doesn't work very well without the other. Nutrition
is with you your entire life.
There are many, many resources available to you. There are books, classes, webinars, lectures, etc. You can hire a nutritionist to help you. Likewise, join a gym and go there 5 times a week. Hire a trainer for the first 2 or3 sessions to show you what to do. There is a lot of help out there for you.