the Kethane mod adds a minable resource called "Kethane" to the game. you can scan planets for Kethane, mine the kethane, then convert the Kethane into either liquid fuel, oxidizer, or monopropellant. The mod has parts in three categories, propulsion, utility, and science. the propulsion part include various sizes of tanks to store the kethane in, as well as a rocket powered by raw kethane. the Utility parts include a large extraction drill and a small extraction drill used for taking the kethane from the ground, two converters (large and small) that wil convert your kethane to other resources at a certain efficiency, and a generator that will generate power from raw kethane. the science parts include 2 radars (large and small) that can be used to scan a planets surface for kethane deposites at a certain altitude. all parts can be used the same way you use any part in the game mid-flight; right click on the part and select the desired function.