if the wind is blowing in a direction, that direction is the windward direction. If the wind is blowing towards some direction, that is the leeward direction.
windward side - it is the side that recieves the wind.
leeward sidde - it is the side where the mountain blocks the wind.
example - hold up your hand (mountain) and blow on it (wind). Only the side closest to you feels your breath - this is the windward side. The side that didn't feel anything is the leeward side.
HOPE IT CAN HELP U......