Received from: Automatically after beginning the first chapter
Step 1: Acquire a silver sword
After a successful escape from the castle, you will be left with virtually nothing and the lack of a silver sword will be the most important. It's best to acquire any at all, as fast as possible. A silver sword is best bought from someone or forged, if only you have the formula. It happens, that you will find the Formula: Witcher's Silver Sword in the chests beside the ship.
In order to reach town, you have to complete A Rough Landing.
From the formula you can find out which materials you need to create the sword: diamond dust, timber, iron ore, silver ore If you were collecting stuff throughout the prologue, the only thing missing should be the silver ore You can easily buy it at the dwarven craftsman Bertold Candeler (M7, 6). You can also forge the sword at his shop. Additionally you can meet two craftsmen outside of town: Cedric (M7, 7) and Sendler (M7, 8).
The mission will end when one of the craftsmen forges the sword.