Whenever you create new schema in visual studio or open the exiting one in BizTalk application you find similar window.
This screen shot is taken form http://msdn.microsoft.com/en-us/library/aa559175%28v=bts.70%29.aspx.
Schema Tree:
From here you can create new node, element and records in schema. When you create new element BizTalk editor let you edit its name. You can change name by selecting element/node root and press F2 key on keyboard or rename from right click popup menu. Be default every element will create in string type, you cans select any element and change its value form property pane.
XSD View. :
The middle area is call XSD view. Its is read only area, we can not update any thing directly form here. It shows what you create in Tree view in Schema format. If you want to change anything you have to update from Tree view or from Properties pane.
Properties window: 
Form this panel you can update the most of properties of element or even Schema its self, It display the properties of selected element, node or record. If you select the schema and then go to property panel you can update properties of schema itself, Usually people update the target UrI for schema in this way.
Properties window: 
Form this panel you can update the most of properties of element or even Schema its self, It display the properties of selected element, node or record. If you select the schema and then go to property panel you can update properties of schema itself, Usually people update the target UrI for schema in this way.