Enter 22 inches, 3 strings and 1.5 for width at nut and bridge. The rest really does not matter. click Submit.
Then on the next page, request PDF Files (multiple pages)
It will automatically download you a PDF file. Print it out, and carefully align the light grey page lines around the margins.
Highlight the following frets with a highlighter:
0 2 4 5 7 9 10 11 12 14 16 17 19 21 22 23 24
Transfer ONLY THOSE FRETS to your fingerboard, and fret away.
Put a marker at 12 and 24 to identify your octaves.
You can use Tiny's info there to double check your measurements with a metric ruler. Or you can go to the StewMac fret calculator and enter 558.8mm (same as 22 inches), specify "dulcimer" and use those same numbers to doublecheck your measurements. It is tricky to keep the paper template accurate at the page break.