How to Train Your Dragon is a book in a book. It is the only book the Hairy Hooligans ever read (until A Hero's Guide to Deadly Dragons). It is used as an instruction manual for training dragons. It is written by Professor Yobbish. It was stolen from the Meathead Public Library by Gobber the Belch (which he takes great pride in).
It is a hard-back book has a very fancy cover that is unusually thick and has golden clasps and very fancy lettering. It is humorously made like a book in modern times, with an "About the Author" section, a library card, a summary on the back, barcode, and reviews.Despite the book's fanciness, it only has three words in the entire text section. "YELL AT IT!" It the only advice it gives, majorly disappointing Hiccup when he reads it.
How to Train Your Dragon 2 is the (fictional) sequel to Professor Yobbish's How to Train Your Dragon. He wrote it after Stoick the Vast send a complaint letter after the events of the first novel. The only difference between the two books is that he added the word "loudly" on the second version.