In order to link textboxes you’ll need to make sure that first they have no text in them. Publisher will not allow you to link text boxes which already have data. There should be a tool bar at the top for linking text boxes (see below).
If this tool bar does not appear then right click in the tool bar area and make sure the “Connect Text Boxes” tool bar is checked.
Now select the first text box that you want to link from. With that text box selected, click the “Create Text Box Link” button (see below).
Now you’ll need to select the text box that you want it to link to and viola you now have linked text boxes. If for some reason you need to unlink text boxes then you can use the “Break Forward Link” button (see below) while selecting the textbox that you no longer want to link from.