Four quick steps.
1. Wipe the can clean
Wipe the spot on the can where the label will go.
2. Peel the backing
Hold the curved label with one hand. Run a finger down to catch the vinyl and peel it away from the backing.
3. Line it up
Hold the label against the can and line it up where you want it.
4. Smooth it with the squeegee
Smooth the label flat with the squeegee. Done.