I hope this pictorial makes it clearer
First, cut your labels to size. You want them at least large enough to cover the ones on the water bottles, if you aren’t taking the labels off.
You may or may not want it long enough to fully wrap around your bottle. If you are printing them off, just don’t let your design go all the way to the edges of your 8 1/2″ paper, it will cover itself up when wrapped around.
Flip your label over, so you are looking at the back side:
Take clear packing tape and cover the back side completely.
Now, you are ready to wrap the bottles!