Place the female end of the hose over the sillcock on the wall and turn clockwise until it tightens. The female end of the hose connection has a rubber washer. Tightening the connection compresses the washer and makes the connection water-tight. To disconnect, turn counterclockwise.
Place the female end of a hose bib between two sections of hose and tighten it the same way you did when you connected the hose to the wall faucet.
Attach the drain hose to a hose bib on the boiler the same way you do for a sillcock or the connection between hoses. Do not screw the female connection on any harder than is necessary to get a drip-free connection. If you cinch it too tightly you can damage the interior washer.