Mystcraft Wikia:Getting Started

Mystcraft allows players to create entire new worlds ("ages") for adventure, settlement, or material gain, or just for fun. While you don't have the level of control described in the original Myst material (Minecraft mechanics don't really allow for that), you will eventually have a fair bit of control over the appearance and contents of your ages. This is gained by collecting and using the mystical symbols that compose the books.

Beginning Mystcraft
Mystcraft does not change overworld generation, except that it adds a few items to the standard loot chests: Symbol pages and sealed symbol packs. The latter are intended to work similarly to the "booster packs" for popular trading-card games such as Magic or Pokemon; the only thing to do with them is to open them for the symbol pages inside. Symbol pages are not strictly neccessary for creating worlds, but without them you can only create completely random worlds. The writing desk will let you copy these pages.

To begin creating ages, you will need some basic resources to create your equipment: wood, stone, iron, leather, glass, paper, and especially ink. (You'll be using a lot of ink, so collect ahead of time.)

Your First World

 * 1) Begin by crafting an ink mixer, a book binder, a folder, and a supply of ink (at least 4 vials).  You may want to create your writing desk while you're at it, but you won't actually need it for your first world.
 * 2) Load the ink mixer with ink and paper, and use it to create two to four link panels.
 * 3) Separate out one of the link panels for later steps.  Craft the others with leather to create unlinked link books.
 * 4) Find a safe place, such as the middle of your workshop or base.  This will be where you return to the Overworld after travel.  Wield your link books one at a time, and 'use' (right-click) them to link them to this spot.
 * 5) Take your last link panel to the book binder and put it in the gray middle area.  Put some leather in the appropriate slot, and choose a name for your world in the textbox at the upper left.  Claim your new descriptive book.

However, playing with such powerful forces will expose players to equally powerful dangers. It is a player's own responsibility to make sure they have a way home, and if they want to avoid harsh or bizarre conditions, they will need to both learn how to write ages correctly, and collect the symbols needed to do so.

Hazards
Poorly (or greedily) written ages can be unstable to varying degrees. Instability can appear in various forms, in rough order of severity: they may be permanently dark, or islands floating in the void, or barren of useful resources.
 * Even beyond outright instability, ages can be otherwise dangerous --

changes to the world rules, such as monsters regenerating or all creatures (including the player) being set afire by sunlight. explosions, and most forms of decay are death sentences for the world, eventually destroying any area where the player stays long enough, and quite likely making the original spawn point unusable. The exact details of how instability is produced have varied greatly over mod versions. In any version, an "incorrectly" written age, or a "greedy" one, will be unstable. The standards for correctness have generally gotten looser over time, while the standards for greed have evolved toward better game balance. As of version 0.10.4, underspecified or random ages aren't intrinsically unstable, but will have random additions which may add instability.
 * The weakest forms if instability are status effects and debuffs that affect players exposed to the sky.
 * The next level adds status effects that affect players even when sheltered or underground.
 * There can also be
 * More seriously unstable ages can face natural hazards: lightning, meteors, or random explosions.
 * The most unstable worlds will face decay, with the landscape rotting into useless blocks, or crumbling away entirely around the player.
 * Meteors,

The tool to return from whence you came is called a Linking Book. Always bring a Linking Book. Or three... that link also has other advice.

Another warning: Whenever you use a book to travel to a new age, the book does not go with you, but stays behind. Protect your books! They are fragile and can go poof! If a book is used from a lectern or bookstand, it will stay there, and be somewhat protected from the environment. However, if a book is used "out of hand" (that is, from your own inventory), it will be left as a special entity in the world you left. These dropped books are not item entities, but appear as open books lying on the ground. They can be used (or picked up) by right-clicking on them, but if left alone, they will take damage from the environment and eventually be destroyed. (This will not occur in unloaded chunks, but be sure the chunk actually is unloaded!)