Show parent and it's children as a nav Newbie here with hopefully a simple question...

I have a structure as per the image below where I want to only show the parent item and it's children on their pages. 

I want to exclude the other entries but they should show on their own pages.
You can access children through the entry's descendants property.

{# display event-information #}
&lt;ul&gt;
    &lt;li&gt;&lt;a href="{{ entry.url }}"&gt;{{ entry.title }}&lt;/a&gt;
    {# display subsections #}
        &lt;ul&gt;
            {% for subsection in entry.descendants %}
                &lt;li&gt;&lt;a href="{{ subsection.url }}"&gt;{{ subsection.title }}&lt;/a&gt;&lt;/li&gt;
            {% endfor %}
        &lt;/ul&gt;
    &lt;/li&gt;
&lt;/ul&gt;


You can also use the nav tag, as described in the documentation.

&lt;ul id="nav"&gt;
    {% nav entry in entries %}
        &lt;li&gt;
            &lt;a href="{{ entry.url }}"&gt;{{ entry.title }}&lt;/a&gt;
            {% ifchildren %}
                &lt;ul&gt;
                    {% children %}
                &lt;/ul&gt;
            {% endifchildren %}
        &lt;/li&gt;
    {% endnav %}
&lt;/ul&gt;


More generally speaking, you can use any of the following properties of the EntryModel to traverse the structure: parent, children, descendants, ancestors, siblings, nextSibling, prevSibling, and level.