It is really so darn simple.
First you need to find some silverware suitable for stamping. In my experience it seems like silverplated silverware is easier to stamp than stainless steel.
I would assume stainless is a harder metal than silverplate, which is a thin layer of silver over top of copper, brass or nickel. I skipped out on Metallurgy 101 though.
Also, if you are going to stamp a knife, be aware that a lot of silverplated knives have stainless steel blades (yet the handles are silverplated). So in my example below I used a butter knife which was totally silverplated (it's all one piece of silverplate rather than the table knife which is sort of two pieces).