Mindy - welcome to the boards! First off, use the "Search" feature - this will help you find lots of info for specific questions. Second, what a great attitude to start off your "adult" life with! (Wish this board was around when I was that age - jeez - your exactly half my age
) The good news is that you are never too old and there is always hope. Frankly, it only gets better! To give you an example of "never too old" - I did a bodybuilding competition where there were 3 guys in the "Over 80" category and two women in the "Over 70" category. A little scary, but how cool is that. One woman was 72 and got into "body building" because she started lifting weights to deal w/ osteoporosis. There was also a woman who got to competition level as part of recovery from cancer.
This is not to say you have to get into bodybuilding competition to enjoy good health....!
The basic thing to understand about "getting into shape" is clean diet & a consistent training & cardio regimen will do wonders. The recommended diet "style" is eating 5-6 small meals per day (or think of it as 3 meals w/ a couple of healthy "snacks" between) so you are eating every 2-3 hours. (Lots of info on this on the Diet board and some on the women's board.) Weight / resistance training will do wonders for strength & fat burning. Cardio helps with better fat loss.
And the whole training & cardio thing is a wonderful stress reliever! (Trust me - it got me through a physics degree and two masters' degrees while working full time.)
If you want to "lose weight", think more in terms of "losing body fat" instead. (Better measure of "fatness".) You might want to get a body fat measurement done at your local gym to give you a reference point for your future efforts. And the most important thing to understand is starvation diets will hurt you more than help you so just be patient and the above "clean diet, training, cardio" thing will give you great results.
Another interesting thing you will find after a while is learning how your body reacts to the general diet/training approaches. Personally, I was always able to build great muscle mass, but at the cost of increased body fat. The only way I lost significant body fat was by doing 45-60 min of cardio 3-4 x/week (+ my clean diet & training) on an empty stomach before breakfast.
... Its a lifestyle!
Hope you learn lots and have fun here!