There are hundreds of combinations of variables that you can consider when designing a workout- resistance, reps, sets, tempo, total time under load, range of motion, rest periods, rep speed, angles of resistance, blah, blah, blah. Nutrition and diet can be equally complicated and confusing- macro nutrient profiles and ratios, micro-nutrient profiles, meal timing, glycemic index, calorie cycling, the best source and form of this, the healthiest way to prepare that. It's enough to make anyone throw their hands up in the air in disgust, grab an ice cream sandwich & can of soda pop and lie down on the couch.

Don't let the information overload discourage you.
Start out with a simple plan to exercise and eat right. If you're just getting started do resistance training and cardio at a level that is appropriate for your level of fitness. Stick to the basics. This applies to you if you are trying to lose fat, gain muscle, improve your health or performance or any combination of these.
Find out the caloric range required for your target weight range and stick to it. Emphasize nutrient rich foods while minimizing the junk from your diet. Be sure to drink enough water to stay well hydrated at all times. You may want to consider a multivitamin, multimineral to make sure you're getting the right amount of nutrients. Again, these simple tips apply to all beginners, regardless of your reason for exercising and eating right.

Don't waste precious time reading, studying and analyzing all the overwhelming amounts of info. Pick a simple plan, get started, and stick with it.