In Unbound Mode, you need to manually create columns and a tree in code:
Columns can be created at design time or in code. For detailed information, see Creating Columns and Binding Them to Data Fields.
Nodes can only be created in code. To create nodes, use the ASPxTreeList.AppendNode method. All you have to do is to specify a unique value that identifies the node, and a parent node for it, if needed. This method will then create the node and place it at the required position within the ASPxTreeList.