If you want to enter plain or formatted text for your items within UR, you will probably want to base your template on the Text core template [1] rather than the Document template.
To set up the derived template, right-click the Templates item, click Insert Child and Text in the drop-down menu. Rename your custom template and add the custom attributes to it via the Item Attributes pane.
To use the template, select the parent item in the tree, insert as above, except choose your new template instead of Text, then edit the item text and attributes as desired. You can also set the Default Child Template attribute of a parent item to your new Template for the default insert (Edit | Insert on the menu or the Insert key) to use that template by default.
The Attributes Editor dialog, for managing attributes, is documented here [2].
[1]
http://www.kinook.com/UR/Manual/?texttemplate.htm
[2]
http://www.kinook.com/UR/Manual/?att...itordialog.htm