You appear to be trying to use DTP techniques (as in Microsoft Publisher) in an image editing program!
You don't need a text box. Simply click on the Type Tool. (It's the big letter 'T'). Then click roughly where you want the text to appear on your image. Type what you want. To change the font, size or colour of the type, highlight it and make the changes as you would in Microsoft Word. To change the position of the text, put the cursor close to it, then 'click & drag'. When you're happy with the result, click on any other tool (such as the Path Component Selection Tool, next to the Type Tool) to complete the operation.
Chris