The following instructions are based on the default settings when you first purchase ToMarket. If you are not seeing the described behavior, check Tools -> Preferences for any settings that may have been changed.
There are three categories of items at the top of the main screen: All Items, Need, and Cart.
All Items is everything on your list. The All Items list has been preloaded with a short list of items to get you started. To see how to add more items click here.
Need is all of the items you currently need and is a sub-set of All Items.
To mark an item as needed, simply touch the item name or the check box on the left. You will then be prompted for a quantity needed (enter quantity and select OK) and then the item status will show a green check mark in both the All Items and Need views.
Cart shows all of the items you have (or will) purchased.
When you are at the store, select the Need tab to get a list of all of the items that you need. To filter by the store you are shopping at and to display Aisle information, select the store name (Grocery in sample above). As you put items into your real cart, select the items on the Need view to move them into your virtual Cart, the third tab.
When moving an item to the Cart, you will be prompted for the quantity purchased (defaulted to the quantity needed) and the cost of the item (defaulted to the current item cost).
When you are finished shopping, select the Cart tab and you will see all of your purchases, along with the total price of your purchases. To reset your Cart to empty, select Menu -> Move Items -> Cart to All
Aisles
To use Aisles, the following item needs to be set:
Menu -> More -> Tools -> Preferences -> Display Info -> Aisles (checked)
And a store must be selected in the top right pull down menu.
In the example below, Bananas has an Aisle associated with it, Aisle 9.
If bananas had no Aisle selected, the Aisle icon would look like this: 
To add an Aisle to an Item/Store, click on the icon to get to this menu:
Choose an Aisle from the list, or type a new Aisle in the box and choose save. The Aisle list shows all currently used Aisles, so if the pull down does not have the aisle you want, just add a new on in the “Create a new aisle here” box.
Remember, Aisles work “per store” which means that they are only assigned and viewable when you have a store chosen. This also means that when you have Apples assigned to aisle1 in Store1, you will see no aisle selected in Store2 (until you set it there too).
To choose Aisles for multiple stores at the same time, go to theStore Chooser.
To get to the Store Chooser:
long press an Item-> Change Stores For Item OR
long press an Item-> Edit This Item -> Save and Edit Stores and Aisles for Item OR
Menu -> Add Item -> Save and Edit Stores and Aisles for Item
Select the blue Aisle icon to bring up the Aisle Chooser menu.
Home of the Android ToMarket Grocery Shopping App!