Hey Kristy - I hear you with the tiredness, I was tired all the time when I was overweight. I used to fall asleep in my office every afternoon at work and I was a zombie on the couch by 9pm or so!
At least you already cook! So many people hate doing anything in the kitchen, you have that going for you
Eating to lose weight is at the heart pretty basic - eat smaller portions, eat more plants, avoid fast foods, fried foods, alcohol, creamy foods and packaged baked goods. Eat lean proteins, complex carbohydrates (sweet potatoes whole wheat pasta whole wheat tortillas quinoa), low fat dairy, lots of fruits and vegetables and healthy fats (walnuts, salmon, avocado, olive oil) everyday. Eating healthy doesn't have to taste bad or boring or bland - I make some awesome stuff - super spicy healthy chili, maple-glazed salmon, delicious home made pizza, home made pasta sauce - my basic rule is 30 minutes/2 pots.
Healthy eating made a huge change in how I FELT (and later - how I looked). Exericse is a great weight-loss component, but what/how much you eat is even more critical. It's a lot easier to NOT eat a 500 calorie muffin than to try to burn 500 calories via exercise (the muffin is just an example).
Portion control is really key - read labels, get a food scale, buy some gorgeous measuring cups (I saw some really pretty powder blue ones that looked like little coffee cups, I wanted them so badly), buy smaller plates, smaller bowls. After 3 years, I STILL measure oatmeal, salad dressing, nuts, cereal, rice, pasta, cheese - I just can't eyeball those items!!
If you eat better, you will FEEL better!