Dorothy,
The most common way to use these is with DW glossy fiber paper dried face up (against the apron) for a semi-gloss finish.
The dryer surface need not be super spotless unless you plan to ferrotype SW prints (which you are not). Bon Ami is a grit-free powdered cleaner available at your local supermarket, next to the Ajax and Comet. Their logo is a baby chick, with the slogan, "Hasn't scratched yet".
The major trick to these dryers is to get the print as EVENLY dry as possible before placing it on the surface. Squeegeeing is not enough. Also wipe front and back with a clean "motel-type" towel.
Prints stretch when wet and shrink as they dry. Wet fingerprints or water droplets will dry more slowly than the rest of the print, causing ripples and dimples.
Also, be very fussy with the amount of fixer hardener and fixing time you use. Over-doing these will over-harden the fiber prints, making them brittle. In extreme cases, this may cause emulsion crazing, as on old pottery. Too little fix will leave the print emulsion surface soft enough to stick to the apron, leaving a flocked surface.