If they are indeed dry-transfers (and it sounds like they are), you've got it right. You'll need some sort of stylus, or burnisher. Hobby shops and drafting supply stores sell tools made for the purpose, bot a ballpoint pen will do the trick.
Peel the protective paper of the back, and hold the number exactly where you want it To be on themodel. Rub the burnisher gently over the number, being careful not to miss any spot. (The color of the number will change slightly as the number comes loose from the cover sheet.) Gently peel off the sheet. If you did it right, the number will stay on the model. Next, take the thin backing sheet that you removed from the back, lay it over the number, and burnish it vigorously. That does it.
It's always a good idea to spray dry transfers with some sort of fixative. Most of the usual flat finishes will work fine, but it's a good idea to do a test shot in some inconspicuous spot to be safe.
Dry transfers have a big advantage over water-slide decals: dry transfers have no carrier film. A dry transfer, carefully applied, will literally look like it was painted on. The drawback is that dry transfers can't be moved around on the surface. Unless you have duplicates, you only get one chance.
Hope that helps.
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