After switching back to the Application Builder mode, you can add buttons by dragging them into the workspace. Keep in mind that in Dashboard Mode, the builder adds all required containers (Tab List, H Splitter, V Splitter) for simplified layout. In Application mode, containers need to be added directly. In this example, I added an H List Box that contains two Button Box objects:
Note that I placed the objects as close to the outer Tab Page title as I could. I would not recommend placing supplementary material like this between reports in a Dashboard, because the report content (Tab Pages and Splitters) can be rearranged in the running dashboard. Modifiying that layout can affect the run-time behavior of the dashboard.
Next, for each button you can add a title and action script from the property panel (open from red-triangle menu or by dragging splitter from the right edge). In this example, I used these commands to open a web resource or local file:
Web("https://www.jmp.com/support/downloads/pdf/jmp_user_guide.pdf")
Open("$SAMPLE_SCRIPTS/bootstrapSample.jsl")
The attached jmpappsource file contains a finished result.