Ext JS 4 – laying out fields in a form using hbox, vbox, etc

I have a simple Ext JS 4 form inside a window (MVC style app). The example below shows 4 fields. This example is simplified, but now I need to take these fields and lay them out using hbox and vbox (and possibly others?)

How would I for example, take the first two fields and put the in a hbox at the top of the form so they display horizontally, at the top of the form, then take the rest of the fields and put them in a vbox below that hbox so they display vertically?

(my actual form has a lot more fields and I will have various other hbox/vboxes, but I am just looking to get started):

Ext.define('ESDB.view.encounter.Edit', {
    extend: 'Ext.window.Window',
    alias : 'widget.encounteredit',
    title : 'Edit Encounter',
    layout: 'fit',
    width: 700,
    autoShow: true,

    initComponent: function() {
        this.items = [

        {
            xtype: 'form',
            items: [
                {
                xtype: 'displayfield',
                name: 'id',
                fieldLabel: 'ID'
                },
                {
                    xtype: 'displayfield',
                    name: 'cid',
                    fieldLabel: 'cid#'
                },
                {
                    xtype: 'displayfield',
                    name: 'addedDate',
                    fieldLabel: 'Added'
                },
                {
                    xtype: 'displayfield',
                    name: 'clientID',
                    fieldLabel: 'Client#'
                }
                     }
     ]

   }

I have looked at various examples of layout sencha page , sencha docs, and finally another one — this last one has something that looks close – in the form tree, fieldsets in 2 columns, it shows a form with items[] and inside there some layout code, and I was able to get that to partially work, but was not able to convert it to an hbox/vbox style layout. When I set it to hbox, there is no height to the hbox, so I can not see the fields.