Adding Multiple Checkbox values to a Label C#

Im currently trying to do my school practical assignment but im facing some issues. Basically what i want to do is to add up the values of the multiple checkboxes. Im doing a food menu.

Here is my code.

//Ingredients Price ONLY

double vegetable = 0.60;
double fishball = 0.90;
double tofu = 0.80;
double mushroom = 1.20;

i dont know what is the next step.

I just started learning visual studio so its best if everything is kept simple. Thanks in advance!