Congratulations! You just finished a tough workout and you're starving! You definitely deserve to refuel and recuperate.
First off, after a tough workout, you should rehydrate immediately. Ideally, you should sip on water throughout your workout but that's not always possible. Additionally, if you just finished an especially intense workout (think more than two hours, two-a-days, or marathon training), you might also want to replenish your electrolytes. Try coconut water for an all-natural sports drink instead of more traditional, artificial ones.
Secondly, consider how many calories you just burnt. A good rule of thumb is to eat roughly half of the total calories burnt throughout your work. This amount will refuel your body but shouldn't interfere with weight loss goals. Just remember to allow for those calories in your daily intake.
Finally, once you've figured out how much you should have for your post-workout snack, eat a mix of carbs and proteins. Your meal should be roughly 60% carbohydrates and 40% protein. Fat is unnecessary and does not play a significant role in workout recovery. However, carbs and proteins definitely do. The glycogen in the carbs will replenish the muscle fuel used during your workout. The protein will keep your body from breaking down muscle tissue for fuel and will initiate muscle recovery and rebuilding.
Ideally, you should eat roughly 30 minutes to 2 hours after your workout. For a good mix of carbs and proteins, try peanut butter toast, nuts and dried fruit, a turkey sandwich, yogurt and granola, or a smoothie. These snacks will have you ready to hit the gym hard again soon!