How to Add a Border Around Your Text Box
First of all, click on your text box so that its selected. Then click the 'Frames' option highlighted in the image.
When you select the frames option you will be able to select 'border' you can add this to the single text box selected or you can choose to do multiple objects. This will apply the border to all text boxes throughout your book.
You can then choose which text boxes and width of border etc.