First steps is one of the books used for the Stargate SG-1 roleplaying game. This volume of the series sets up a bunch of unexplored worlds that the gamemaster can set as the background for the game. Each world has various physical characters, but what makes it interesting reading, even if you don't actually play the game, is the description of the various planets as far as their history and culture goes.
Eldeore: Planet with a civilization nearly totally destroyed by science used for destructive purposes. Civilization was rebuilt with science strictly controlled in its uses. They also developed a way to genetically repress violent tendencies and developed into a utopian society.
Gallicia: Developed a civilization like Moracco. Very religious. Tolerant of others and polygamy and polyandry are both allowed.
Hidoma: Founded using people taken from Japan. The system lord was using them, got caught and was ordered to destroy the planet. He wiped out over 90% of the people. Survivors managed to restart society into a farming and a city form of life.
Himmel: Apparently the Nazis had the stargate for a while and managed to get it to work. Nazi SS troops were sent to the planet and fought the beings working for the system lord. The system lord ended up being killed later, and the Nazis are now in still in a fight with the other beings that had worked for the system lord.
Hou Kainga: Founded using Polynesian humans. Because of a very limited space for population expansion, the civilization has not grown much and remains at a fairly primitive level.
Lira-Ke: A planet under the firm control of a system lord and that is used to construct parts of ships, train spies, etc. The society is prosperous, but five times a year assassins are allowed to kill anyone they want, basically as a form of training.
Longinus: The planet is used by system lords to have their armies of human slaves battle each other as a form of entertainment.
Makkahn Ahk: The inhabitants of the original planet were Unas who had developed a civilization of their own. They established a base on another world, though, expecting a system lord to attack them eventually, and Apophis did just that.
Shchizenya: A Chinese nomadic tribe was taken by a system lord. He educated them and they eventually rebelled, killing him and taking his ship to a planet where they hoped to stay away from threats from space. They developed an advanced civilization but eventually destroyed themselves in a civil war. The nanite structure they had left on the planet, fed energy by orbiting satellites, eventually evolved into a life form of its own.
Stennos: A system lord used the planet for its naquadah mines. As groups of humans revolted he slaughtered them. One group pledged their loyalty and became the 'chosen' of the planet.
An Asgard ship later fought other Gou'ald ships, destroying them, but crashing as a result. The Asgard died, and transferred only part of his conscious to a clone which ended up believing he was the god that the chosen expected to return.
The book also contains scenarios for space activities, new rules for the game and chases and vehicle guides.
There are also photos from the regular SG-1 TV show.