Sencha touch 2.3 Form

I want to create a form in sencha touch. I'm using json file to get data.

How to load data to textfield from store?

I tried these ways. like in example. But in example they used itemTpl.

Code:

config: {
        itemId: 'profile',
        title: 'profile',
        store: 'ProfileStore',
        scrollable : {
            direction     : 'vertical',
            directionLock : true
        },
        items: [
            {
                xtype: 'textfield',
                name: 'firstName',
                label: 'First Name',
                emptyText: '',
                required: true,
                controlType: 'TextBox',
                data: '{firstName}'
            },
            {
                xtype: 'textfield',
                name: 'firstName',
                label: 'First Name',
                emptyText: '',
                required: true,
                controlType: 'TextBox',
                value: '{firstName}'
            }

But it is not working. Please help me. If you have example please give link.

Thanks in advance.

Sencha touch 2.3 Form