The skinny end goes in the slot, you pound on the thick end. The force exerted by the wedge will push the tree in exactly the same direction as the wedge points. Its not a whole lot different that driving a nail, you shouldn't need to read a book to figure it out.
Sometimes yes, sometimes not Kong. Butt you're correct about the book thing: it takes doing it. Again, and again.
Dropping a leaner with wedges can be tricky. Depends on DBH, species (hard or soft), crown, LZ, rot, feller's experience, etc... Not just "The skinny end....". And, it can be whole different experience with frozen ( well north of WV :hmm3grin2orange::monkey: ) wood.
The CPL and Game of Logging courses ( well worth the time and $$$$ BTW for anyone Kong ) spend some time with wedge use dropping leaners OPPOSITE to the direction of lean. There's a method to determining the 'lift' and wedge placement based on the angle of lean, the crown weight and direction, height of the beast, bored cuts for efficiency, etc... No, it ain't just "The skinny end...".
For us, wedges are part of the belt pack. Used often even in non leaners for greater control. You got to try it.
JMNSHO