Ok, I'm back home. Let's get more detailed
Inside quest_protype.lsx, you will find this tags:
<node id ="Quest">
<attribute id="QuestID" value="Diary" type="22"/>
<attribute id="MainQuest" value="1" type="19"/>
<attribute id="QuestTitle" value="Diary_Title" type="22"/>
<children>
<node id ="QuestState">
<attribute id="Status" value="Update1" type="22"/>
<attribute id="Description" value="Diary_Update1_descr" type="22"/>
<attribute id="Rewards" value="" type="22"/>
<attribute id="Marker" value="" type="22"/>
<attribute id="Achievement" value="quest1" type="22"/>
<attribute id="Act" value="" type="4"/>
<attribute id="Gain" value="" type="4"/>
<attribute id="ReputationGain" value="" type="4"/>
</node>
</children>
</node>
This is the essential you need to make a quest work. Now the important things you need to know about the code:
QuestID will be used in the Story Editor script, for QuestAdd() and QuestUpdate().
QuestTitle will be used in the TranslatedKey Editor to show the title in your Journal.
The node QuestState will be used for any of the update your quest will have, so if you want to add another update, you have to make another node.
Similar to QuestTitle, the attribute Description will be used to show the description text inside the quest. Go in the TranslatedKey Editor and as a value use Diary_Update1_descr(it's an example, you can use your own string there).
The Status Attribute will be used for the QuestUpdate() command. In this case QuestUpdate("Diary", "Update1");
If you want the update to give exp you need to set Act value to 1 and Gain to whatever you want.
The other attributes are still pretty obscure to me, but this the essential you need to know to make it work.