software of food and biling system

[sumisimmy]

i have to make a software product on food an billing system in C language..plz help me..

[Moschops]

Show user list of food.
Get from user how much of which food.
Show user the cost.

How far have you got so far?

[whitech]

The solution is easy.Just show us what you did so far.If you didn't write anything,try to decide what kind of information you will use on your software.I mean determine the variables such as

double bill_amount;
double food_stock;

[sumisimmy]

i want to know how i will strt making it ?
i hav to design a software product using C language and i hav to make some products in it like:-
1.atleastone GUI based input
2.atleast one GUI base output
3.atleast one printable output
4.3 or 4 validation test for extreme data
5.file/table design
6.final product(implentable through the .exe file)