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Step - 3 : Create new screen by name personForm and include this list form in it.

<screen name="PersonForm">
        <section>
            <actions>
                <set field="headerItem" value="personForm"/>
                <set field="titleProperty" value="PageTitlePracticePersonForm"/>
                <entity-condition entity-name="Person" list="persons"/>
            </actions>
            <widgets>
                <decorator-screen name="CommonPracticeDecorator" location="${parameters.mainDecoratorLocation}">
                    <decorator-section name="body">
                        <label text="Person List" style="h2"/>
                        <include-form name="ListPersons" location="component://practice/widget/PracticeForms.xml"></include-form>
                    </decorator-section>
                </decorator-screen>       
            </widgets>
        </section>
</screen>

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Step - 1 : Create screen by name "main-decorator" in CommonScreens.xml file.(Take reference from CommonScreens.xml file of Example component.)

<screen name="main-decorator">
        <section>
            <actions>
                <property-map resource="CommonUiLabels" map-name="uiLabelMap" global="true"/>
                <property-map resource="PracticeUiLabels" map-name="uiLabelMap" global="true"/>
                <set field="layoutSettings.companyName" from-field="uiLabelMap.PracticeCompanyName" global="true"/>
                <set field="activeApp" value="practice" global="true"/>
                <set field="applicationMenuName" value="PracticeAppBar" global="true"/>
                <set field="applicationMenuLocation" value="component://practice/widget/PracticeMenus.xml" global="true"/>
            </actions>
            <widgets>
                <include-screen name="GlobalDecorator" location="component://common/widget/CommonScreens.xml"/>
            </widgets>
        </section>
</screen>

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*Step - 1 :*For this create directory by name "config" in your component directory i.e. "practice".
Note: -Here remember to create an entry for the config directory in your ofbiz-component.xml file.
which will be :

<classpath type="dir" location="config"/>

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Step - 3: Include this UI Label resource in your main decorator screen which you created earlier and use these one or two ui labels which you are having now.Step - 4 : Use those 2 UI labels at appropriate places.
Note : Always search first for any existing Ui label in ofbiz and if you don't find it there then only create new one.Output Screen:

Now its time to make this practice application secure by checking authentication (user login):

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Step - 2 :  Make changes in requests in controller.xml file make auth="true" means now these requests needs authentication.
This is first security level which you have implemented. you request should look like :

<request-map uri="main">
    <security https="true" auth="true"/>
    <response name="success" type="view" value="main"/>
    <response name="error" type="view" value="main"/>
</request-map>

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7.b : Create some Ui labels for showing them in fail-property like PracticeFirstNameMissingError.
7.c : Now call service createPracticePerson service by passing out map which is obtained after processing fields as a in map to the service.
OutPut Screen :

Part - 4

Java Event:

Here the java event which you will be writing will be fairly simple. For reference you can check any of the *Events.java file.
Step - 1 : The contents will be :

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ECA : It is a combinition of 3 things: an event, conditions per event, and actions per event. It is a rule used to trigger an action upon the execution of an event when certain conditions are met. When a service is called for example a lookup is performed to see if any ECAs are defined for this event. Events include before authentication, before IN parameter validation, before actual service invocation, before OUT parameter validation, before transaction commit, or before the service returns. Next, each condition in the ECA definition is evaluated and if all come back as true, each action is performed. An action is just a service which must be defined to work with the parameters already in the service's context. There is no limit to the number of conditions or actions each ECA may define.
For more details on this visit :  http://docs.ofbiz.org/display/OFBTECH/Service + Engine + Guide
1. SECA (Service Event Condition Action) : This is used when we want to trigger another service(action) on the execution of a service when certain conditions are met.
2. EECA (Entity Event Condition Action) : This is used when we want to trigger a service on the creation of a record for an entity when certain conditions are met.
For the implementation of ECA again we will be following the same approach for screens, menus by following steps:
Step - 1 : Add one more application menu named "ECA" to the practice application's menu bar.(Do the needful entries for target in controller.xml)
Step - 2 : Now create another menu called "EcaMenu" in the PracticeMenus.xml file. This menu will have two menu items named "seca" and "eeca". For each of these, two screens will be needed that use the "CreatePerson" form which we created above. (in personForm screen)

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If you have followed all the steps and developed practice application from this application then this will really help you in understanding other implementations in OFBiz. These things are basic foundation of working in OFBiz. Now you know that how you can start the development in OFBiz. Don't leave the extra links provided in this tutorial as they will really help you a lot in understanding the things which are there.
Here is another good reading will be help you a lot is available at FAQ Tips Tricks Cookbook HowTo 
Now the next thing comes in mind is the business process which is really needed to work on, so for this books are available at : http://docs.ofbiz.org/display/OFBADMIN/OFBiz + Related + Books/