Every gaming platform has its own way it works, and every game has its own currency.
Take World of Warcraft as one example: you need gold to learn anything, be it the riding skill, professions or your spells and abilities. If you are playing League of Legends, you can buy things with either Influence points of Riot points. The influence points are earned for playing games, while the Riot Points are only acquirable for real currency. The Windows live platform, which operates the Xbox Live, has a similar system, where you will pay a monthly fee in order to play games. There is also a free version of this, but many features will stay locked, like multiplayer gaming or party chat and more. Even though many people dislike the Live platform because of it, the fee isn’t too expensive, so most people can afford it. In addition, you can acquire microsoft points so you can buy various things you like.
You have surely heard about Live Avatars, that differ from other services because they are 3D and animated, and you can buy various things for them. You can do this either by buying Microsoft points or by unlocking different achievements while you are playing games. You can style your avatar so it has looks similar to you, or you can do something completely different. If you can’t purchase any points, try searching for some websites that offer free microsoft points codes and other prizes in giveaways, and hope you will be the lucky winner.