New to counting calories

Just joined myfitnesspal yesterday. I am 60-70 pounds overweight.. I will lose some weight and gain it back. Does anyone have any tips or advice they can give me… I have always counted carbs so counting calories is new to me. What are some good low cal snacks,breakfast,lunch and dinner? I did not feel hungrey when I counted carbs. Does anyone drink diet soda? With counting calories and exercise when will I start see results? HELP!