The For Dummies series of books is a popular way of learning just about anything, from C++ programming to Divorce Law to African-American History, achieved by simple explanations.
As a result of their popularity, these books are often parodied, and fictional entries to the series are often conjured into existence. This is often done to show that a character knows next to nothing about a subject but is now trying to find out. They will occasionally be ludicrously specific to the task the character is attempting at the time.
Works created before the "For Dummies" series was started will use titles like "How to Do Tropes in N Easy Steps" or "You, Too, Can Trope!" or "Hey, You're not a Genius. Who Cares? Read This and You Won't Suck at X" or "Everything You Always Wanted to Know About Tropes But Were Afraid to Ask." Often, titles may also parody the "Complete Idiot's Guide to _______" series as well.
Compare Correspondence Course, its brother in self-education. Also compare Snowclone and The Joy of X, which lead to similar titling conventions.
The Waterboy used the rival learning series "Complete Idiot's Guide" with "The Complete Idiot's Guide to Football" being read by the incompetent football coach, who is then mocked when the rival competent coach is seen reading the exact same book and laughing.
Bride Of Chucky has Tiffany resurrecting Chucky from the dead through knowledge from a "Voodoo for Dummies" book.
Kirk, from Hoodwinked, doesn't even know which part of an ax goes toward the wood. Fortunately, he finds a copy of Chopping For Actors.
An Ur Example could be the 1968 British comedy film The Bliss of Mrs. Blossom. The main character's lover — who lives secretly in her attic — uses a series of dubious Do-It-Yourself manuals to build all sorts of items there, including a room-size mainframe computer.
In Charmed season 6 episode "The Courtship of Wyatt's Father" Elder Gideon presents a page in a book titled "Everything You Always Wanted to Know About Portals But Were Afraid to Ask."
The Investigation Discovery channel has a commercial for their week of specials about Black Widows that has a woman at the register with normal Thanksgiving stuff, but the last thing the cashier scans is a book called "Killing Your Husband for Dummies".
Roger in Foxtrot tries to buy an actual For Dummies book, but can't bring himself to pronounce the name and admit himself a "dummy", instead asking for a book for "college-educated professionals who majored in the humanities before computers existed."
In Dilbert, when the company produces a product that doesn't work and its instruction manual is complete fiction. The Pointy-Headed Boss's reply: "Ship it and hope someone publishes a 'For Dummies' guide."
Forgotten Realms has something close — canonically, Volo's Guides are an awful mix of brilliant investigations and silly hearsay. The most infamous was "Volo's Guide to All Things Magical", the "second edition" of which claimed that v 1.0 contained a lot of recipes how to kill oneself in a funny way — and so much of sensitive information that Volo hesitated to introduce himself in a hearing range of other wizards ever after, and Elminster had to personally hunt down and destroy every last copy.
Cover art of d20 Modern Arcana SRDnote visible in full resolution if downloaded (it's free) from Infinite Dreamers has a horned greenish lad reading "13 Easy Steps To Overthrow Your Demonic Master", with a readable annotation traditional for this sort of literature on its back cover.
The somewhat free MMO Roblox once had a hat for sale with the title Quantum Thermodynamics for Dummies. It was, indeed, a "For Dummies"-style book that could be worn as a hat (just a mesh, though, so you couldn't read it or anything...).
The Binding of Isaac features the "Telepathy For Dummies" power-up, granting homing tears for a single room upon use.
Unraveling God had a bookshelf which, along with a couple more serious-sounding books, sported a copy of Cellular Molecular Biology for Dummies, Volume 1.
Rose also mentions getting Knitting for Assholes after getting her yarn and knitting needles from John as a birthday gift.
In The Order of the Stick, Vaarsuvius is looking for a way to regain spellcasting power without sleeping, due to a recurring nightmare. The rules of the OOTS universe says a spellcaster needs to rest rather than sleep to regain spells, so Vaarsuvius needs something not mentally taxing that would still help his/her ongoing research into finding Haley. Finding Plot Holesfor Dummies does the trick.
Also, Xykon's line from Start of Darkness: "This magic is in my bones, not cribbed off of Magic for Dummies."
Slackerz has a great example. One of the characters attempted to program his own game called Matt's Kickass Game for Winners (a reference to Strong Bad's Cool Game for Attractive People) However, he knows absolutely nothing about programming. So he consults a regular programming book, a For Dummies book, and a book called Grover's Magical C++ Garden. (He even denounces that as too difficult.)
The Emperor's New Clones, the second Star Wars parody from Backyard Productions, features Vader reading "The Dark Side for Dummies", and Han Solo's father checking "The Star Wars Guide to Techno-Babble".
One episode has Homer going to a book fair, with an entire library of Books for Dummies where he is quite at home.
When the Simpsons go to Brazil, Bart learns Spanish on the flight there, which is "Espaņol para Dummies" with Bumblebee Man as the instructor. Marge is quick to point out that Brazilians speak Portuguese, causing Bart to fly off in an angry rant in Spanish.
Megas XLR with The Complete Moron's Guide To Picking Up Space Chicks.
SpongeBob SquarePants, in episode "Rodeo Daze", has a book titled How to Open Things. Spongebob can't open Sandy's door, but Patrick brings out the book. It conveniently has a whole page about Sandy's door. Also, Spongebob claims to have seen The Film of the Book of How to Open Things.
Planes: Chug briefly reads Air Racing for Dummies at the beginning.