My Cute Cousin (see here)cut the vinyl for me, and I bought the plate at walmart.
Step 1: Clean Plate
Step 2: Apply Vinyl to bottom of plate
Step 3: Apply a generous amount of Armour Etch Cream where you want something etched. (Armour Etch is available at most craft stores: Roberts, Joanne's, Michaels etc...
Step 4: Let cream sit for 5 minutes.
Step 5: Wash off plate with tap water
Step 6: Peel off Vinyl and wash entire Plate (Don't be nervous when you first peel off vinyl it looks like your image didn't work. The plate has to dry to see your design).
Step 7: Clean plate with glass cleaner