Need help creating custom food

Hi, i ve tried to create a new custom food, but i can't seem to list ingredients, to let the program cwlculate calories and carbs.I make my own smoothies at home, so i have no store bought product i can compare it to.I do not know any nutritional information i can add because this app does not let you combine things..or does it?

All i wanted to do is combine frozen miced berries,a packet of stevia sweetner and like 2oz of half snd half.How can i turn all that into one whole food/drink