Apply it according to the instructions on the label of whatever product you buy. You will either need a clean handsprayer to apply a concentrate you will dilute in the sprayer or the product may come on a hose end sprayer. Either way, follow the label instructions and you should be fine. Do your best to apply evenly.
"The Poor Fish" circa 1930's: The Poor Fish wouldn't have been caught if he'd known enough to keep his fool mouth shut.