iCashier an android application

Its an android application that I need for a school project. The app must have login the sign up that connected to a [login to view URL] login the user have the choice to add item and give it a price and [login to view URL] example if the user have a grocery store and want to add item like apple and the price for one is 1$. If the user wants he can update the items or delete them. Then when a grocery store customer come and the user registerd his orders like 2 apples one plastic bag etc. He will press finish button that will show a bill on the screen with the orders and total price. I want a simple app not very professional. Last thing when a user want to register he must put the following information business name, username,email and password. And all the purchases must be saved in the database.