Notes to Tabliture

I think what you want takes more than an hour to learn.
Please list step by step what you did, so we can help you.
Plus you may need to spend some time in the manual.

I'm guessing you created a new score rather than simply adding an instrument to your existing score. To add an instrument, see Edit / Instruments, not File / New. In that dialog, add banjo tablature as your instrument. Then copy and paste the music from the existing staff to the new instrument.

Do note, it's pretty unlikely the PDF import was error-free, and also, since standard notation lacks the information needed for tablature (and vice versa!), the chances of actually getting readable tab this way are pretty low. Not without more extensive editing, anyhow. But it's certainly worth a shot as a starting point.

If you need further help, please attach your score and describe what specifically you are stuck on, so we can understand and assist better.