If you just want to get a feel for Pern, start by reading Dragonflight (Dragonriders of Pern - Volume 1)
Here's a brief summary of what sort of world Pern is:
Pern is a very low-tech, agrarian world; there is no industry, no complex machinery, not even electricity. When you create your character here, you should take these things into consideration. It is also a mostly peaceful world; although most people may carry a belt knife, and sometimes people will get into one-on-one combat, for the most part everyone is cooperative.
They have to be, to survive Thread.
What is Thread? Thread is an alien organism that is spawned on a neighboring planet (the Red Star). As the Red Star swings past Pern every 200 years, it flings off these spores which travel through space and descend on Pern, unraveling in the atmosphere and forming silvery threadlike filaments. When the Threads hit the ground, they'll eat anything living... be it vegetation, animals, or humans.
Thread drowns in water, and can be seared by flame, so Pern's original colonists used genetic engineering to alter an indigenous lifeform, firelizards, to make much larger creatures, which became known as dragons, after the Earth legends they resemble. Dragons have wings, can spew flame (after ingesting a flame-inducing rock native to Pern, known as firestone), and have an uncanny ability to teleport between places... even halfway around the planet.
When a dragon hatches, it chooses a human lifemate to be its rider and caretaker. The two are linked forever, able to communicate telepathically with one another. When the young dragon matures, it learns to chew firestone, and can flame the deadly Threads out of the sky. The bond between dragon and rider is so close, that if the rider dies, the dragon goes between permanently, killing itself.
Dragons and their riders live in remote, extinct volcano calderas known as Weyrs. Holds are where non-riders live, and house the agricultural population of Pern. Holds are what feeds the rest of Pern. In exchange for the Weyr's protection against Threadfall, the Holds in a Weyr's territory donate food and clothing and materials to keep the Weyr's population alive, since dragonriders are too busy fighting thread and caring for their dragons to raise crops or produce things essential to living. This is called a tithe.
One final area where people reside on Pern is a Crafthall. There are many different Crafts specializing in different areas, such as harpers, healers, smiths, miners, herders, tanners, vintners, and others. Crafts also contribute their skills, goods, and/or services to the Weyr that protects them, as well as to Holds all over Pern, in return for food and raw materials from the Holds.
Firelizards, the tiny cousins of dragons, are common pets for Pernese. They are not telepathic, only empathic, but can fly and go between. They're a little like cats, affectionate but independent, and always getting into trouble. To impress a firelizard, a person must be present when their eggs hatch. It isn't possible to impress a grown firelizard.
Harper's Tale exists on and around Ista Island, which is only a small part of Pern. We have not built Pern in its entirety, because we lack the players to populate such a large virtual space, and we also feel that a smaller environment leads to more roleplay and better interaction among players. You may want to refer to the maps of the Ista area to see where things are.